X-Git-Url: https://gitweb.michael.orlitzky.com/?a=blobdiff_plain;f=src%2Fapply-default-acl.c;h=0f7e9ae91deb8c477c0fbae6b8161fc8d6fa2850;hb=40f86500e755883aaa824dba16743bc89d693a42;hp=4f7b3b06a0e1f2cc835038f5701550c57c696859;hpb=1504070cadf122c8d3de0d15a0e2fd35f81eb576;p=apply-default-acl.git

diff --git a/src/apply-default-acl.c b/src/apply-default-acl.c
index 4f7b3b0..0f7e9ae 100644
--- a/src/apply-default-acl.c
+++ b/src/apply-default-acl.c
@@ -1,5 +1,13 @@
+/**
+ * @file apply-default-acl.c
+ *
+ * @brief The entire implementation.
+ *
+ */
+
 /* On Linux, ftw.h needs this special voodoo to work. */
 #define _XOPEN_SOURCE 500
+#define _GNU_SOURCE
 
 #include <errno.h>
 #include <ftw.h>    /* nftw() et al. */
@@ -18,15 +26,24 @@
 #include <sys/types.h>
 #include <sys/acl.h>
 
+/* Most of the libacl functions return 1 for success, 0 for failure,
+   and -1 on error */
+#define ACL_ERROR -1
+#define ACL_FAILURE 0
+#define ACL_SUCCESS 1
 
-/* Command-line options */
-static bool no_exec_mask = false;
 
 
+/**
+ * @brief Get the mode bits from the given path.
+ *
+ * @param path
+ *   The path (file or directory) whose mode we want.
+ *
+ * @return A mode_t (st_mode) structure containing the mode bits.
+ *   See sys/stat.h for details.
+ */
 mode_t get_mode(const char* path) {
-  /*
-   * Get the mode bits from path.
-   */
   if (path == NULL) {
     errno = ENOENT;
     return -1;
@@ -45,10 +62,16 @@ mode_t get_mode(const char* path) {
 }
 
 
+
+/**
+ * @brief Determine whether or not the given path is a regular file.
+ *
+ * @param path
+ *   The path to test.
+ *
+ * @return true if @c path is a regular file, false otherwise.
+ */
 bool is_regular_file(const char* path) {
-  /*
-   * Returns true if path is a regular file, false otherwise.
-   */
   if (path == NULL) {
     return false;
   }
@@ -63,10 +86,17 @@ bool is_regular_file(const char* path) {
   }
 }
 
+
+
+/**
+ * @brief Determine whether or not the given path is a directory.
+ *
+ * @param path
+ *   The path to test.
+ *
+ * @return true if @c path is a directory, false otherwise.
+ */
 bool is_directory(const char* path) {
-  /*
-   * Returns true if path is a directory, false otherwise.
-   */
   if (path == NULL) {
     return false;
   }
@@ -83,37 +113,58 @@ bool is_directory(const char* path) {
 
 
 
+/**
+ * @brief Update (or create) an entry in an @b minimal ACL.
+ *
+ * This function will not work if @c aclp contains extended
+ * entries. This is fine for our purposes, since we call @c wipe_acls
+ * on each path before applying the default to it.
+ *
+ * The assumption that there are no extended entries makes things much
+ * simpler. For example, we only have to update the @c ACL_USER_OBJ,
+ * @c ACL_GROUP_OBJ, and @c ACL_OTHER entries -- all others can simply
+ * be created anew. This means we don't have to fool around comparing
+ * named-user/group entries.
+ *
+ * @param aclp
+ *   A pointer to the acl_t structure whose entry we want to modify.
+ *
+ * @param entry
+ *   The new entry. If @c entry contains a user/group/other entry, we
+ *   update the existing one. Otherwise we create a new entry.
+ *
+ * @return If there is an unexpected library error, @c ACL_ERROR is
+ *   returned. Otherwise, @c ACL_SUCCESS.
+ *
+ */
 int acl_set_entry(acl_t* aclp,
 		  acl_entry_t entry) {
-  /*
-   * Update or create the given entry.
-   */
 
   acl_tag_t entry_tag;
   int gt_result = acl_get_tag_type(entry, &entry_tag);
-  if (gt_result == -1) {
+  if (gt_result == ACL_ERROR) {
     perror("acl_set_entry (acl_get_tag_type)");
-    return -1;
+    return ACL_ERROR;
   }
 
   acl_permset_t entry_permset;
   int ps_result = acl_get_permset(entry, &entry_permset);
-  if (ps_result == -1) {
+  if (ps_result == ACL_ERROR) {
     perror("acl_set_entry (acl_get_permset)");
-    return -1;
+    return ACL_ERROR;
   }
 
   acl_entry_t existing_entry;
   /* Loop through the given ACL looking for matching entries. */
   int result = acl_get_entry(*aclp, ACL_FIRST_ENTRY, &existing_entry);
 
-  while (result == 1) {
+  while (result == ACL_SUCCESS) {
     acl_tag_t existing_tag = ACL_UNDEFINED_TAG;
     int tag_result = acl_get_tag_type(existing_entry, &existing_tag);
 
-    if (tag_result == -1) {
+    if (tag_result == ACL_ERROR) {
        perror("set_acl_tag_permset (acl_get_tag_type)");
-       return -1;
+       return ACL_ERROR;
     }
 
     if (existing_tag == entry_tag) {
@@ -121,21 +172,23 @@ int acl_set_entry(acl_t* aclp,
 	  entry_tag == ACL_GROUP_OBJ ||
 	  entry_tag == ACL_OTHER) {
 	/* Only update for these three since all other tags will have
-	   been wiped. */
+	   been wiped. These three are guaranteed to exist, so if we
+	   match one of them, we're allowed to return ACL_SUCCESS
+	   below and bypass the rest of the function. */
 	acl_permset_t existing_permset;
 	int gep_result = acl_get_permset(existing_entry, &existing_permset);
-	if (gep_result == -1) {
+	if (gep_result == ACL_ERROR) {
 	  perror("acl_set_entry (acl_get_permset)");
-	  return -1;
+	  return ACL_ERROR;
 	}
 
 	int s_result = acl_set_permset(existing_entry, entry_permset);
-	if (s_result == -1) {
+	if (s_result == ACL_ERROR) {
 	  perror("acl_set_entry (acl_set_permset)");
-	  return -1;
+	  return ACL_ERROR;
 	}
 
-	return 1;
+	return ACL_SUCCESS;
       }
 
     }
@@ -145,9 +198,9 @@ int acl_set_entry(acl_t* aclp,
 
   /* This catches both the initial acl_get_entry and the ones at the
      end of the loop. */
-  if (result == -1) {
+  if (result == ACL_ERROR) {
     perror("acl_set_entry (acl_get_entry)");
-    return -1;
+    return ACL_ERROR;
   }
 
   /* If we've made it this far, we need to add a new entry to the
@@ -156,21 +209,21 @@ int acl_set_entry(acl_t* aclp,
 
   /* We allocate memory here that we should release! */
   int c_result = acl_create_entry(aclp, &new_entry);
-  if (c_result == -1) {
+  if (c_result == ACL_ERROR) {
     perror("acl_set_entry (acl_create_entry)");
-    return -1;
+    return ACL_ERROR;
   }
 
   int st_result = acl_set_tag_type(new_entry, entry_tag);
-  if (st_result == -1) {
+  if (st_result == ACL_ERROR) {
     perror("acl_set_entry (acl_set_tag_type)");
-    return -1;
+    return ACL_ERROR;
   }
 
   int s_result = acl_set_permset(new_entry, entry_permset);
-  if (s_result == -1) {
+  if (s_result == ACL_ERROR) {
     perror("acl_set_entry (acl_set_permset)");
-    return -1;
+    return ACL_ERROR;
   }
 
   if (entry_tag == ACL_USER || entry_tag == ACL_GROUP) {
@@ -178,87 +231,118 @@ int acl_set_entry(acl_t* aclp,
     void* entry_qual = acl_get_qualifier(entry);
     if (entry_qual == (void*)NULL) {
       perror("acl_set_entry (acl_get_qualifier)");
-      return -1;
+      return ACL_ERROR;
     }
 
     int sq_result = acl_set_qualifier(new_entry, entry_qual);
-    if (sq_result == -1) {
+    if (sq_result == ACL_ERROR) {
       perror("acl_set_entry (acl_set_qualifier)");
-      return -1;
+      return ACL_ERROR;
     }
   }
 
-  return 1;
+  return ACL_SUCCESS;
 }
 
 
 
+/**
+ * @brief Determine the number of entries in the given ACL.
+ *
+ * @param acl
+ *   A pointer to an @c acl_t structure.
+ *
+ * @return Either the non-negative number of entries in @c acl, or
+ *   @c ACL_ERROR on error.
+ */
 int acl_entry_count(acl_t* acl) {
-  /*
-   * Return the number of entries in acl, or -1 on error.
-   */
+
   acl_entry_t entry;
   int entry_count = 0;
   int result = acl_get_entry(*acl, ACL_FIRST_ENTRY, &entry);
 
-  while (result == 1) {
+  while (result == ACL_SUCCESS) {
     entry_count++;
     result = acl_get_entry(*acl, ACL_NEXT_ENTRY, &entry);
   }
 
-  if (result == -1) {
-    perror("acl_is_minimal (acl_get_entry)");
-    return -1;
+  if (result == ACL_ERROR) {
+    perror("acl_entry_count (acl_get_entry)");
+    return ACL_ERROR;
   }
 
   return entry_count;
 }
 
 
+
+/**
+ * @brief Determine whether or not the given ACL is minimal.
+ *
+ * An ACL is minimal if it has fewer than four entries.
+ *
+ * @param acl
+ *   A pointer to an acl_t structure.
+ *
+ * @return
+ *   - @c ACL_SUCCESS - @c acl is minimal
+ *   - @c ACL_FAILURE - @c acl is not minimal
+ *   - @c ACL_ERROR - Unexpected library error
+ */
 int acl_is_minimal(acl_t* acl) {
-  /* An ACL is minimal if it has fewer than four entries. Return 0 for
-   * false, 1 for true, and -1 on error.
-   */
 
   int ec = acl_entry_count(acl);
-  if (ec == -1) {
+
+  if (ec == ACL_ERROR) {
     perror("acl_is_minimal (acl_entry_count)");
-    return -1;
+    return ACL_ERROR;
   }
 
   if (ec < 4) {
-    return 1;
+    return ACL_SUCCESS;
   }
   else {
-    return 0;
+    return ACL_FAILURE;
   }
 }
 
 
+
+/**
+ * @brief Determine whether the given path has an ACL whose mask
+ *   denies execute.
+ *
+ * @param path
+ *   The path to check.
+ *
+ * @return
+ *   - @c ACL_SUCCESS - @c path has a mask which denies execute.
+ *   - @c ACL_FAILURE - The ACL for @c path does not deny execute,
+ *     or @c path has no extended ACL at all.
+ *   - @c ACL_ERROR - Unexpected library error.
+ */
 int acl_execute_masked(const char* path) {
-  /* Returns 1 i the given path has an ACL mask which denies
-     execute. Returns 0 if it does not (or if it has no ACL/mask at
-     all), and -1 on error. */
 
   acl_t acl = acl_get_file(path, ACL_TYPE_ACCESS);
 
   if (acl == (acl_t)NULL) {
-    return 0;
+    perror("acl_execute_masked (acl_get_file)");
+    return ACL_ERROR;
   }
 
   /* Our return value. */
-  int result = 0;
+  int result = ACL_FAILURE;
 
   acl_entry_t entry;
   int ge_result = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
 
-  while (ge_result == 1) {
+  while (ge_result == ACL_SUCCESS) {
     acl_tag_t tag = ACL_UNDEFINED_TAG;
     int tag_result = acl_get_tag_type(entry, &tag);
 
-    if (tag_result == -1) {
+    if (tag_result == ACL_ERROR) {
        perror("acl_execute_masked (acl_get_tag_type)");
-       result = -1;
+       result = ACL_ERROR;
        goto cleanup;
     }
 
@@ -268,22 +352,22 @@ int acl_execute_masked(const char* path) {
       acl_permset_t permset;
 
       int ps_result = acl_get_permset(entry, &permset);
-      if (ps_result == -1) {
+      if (ps_result == ACL_ERROR) {
 	perror("acl_execute_masked (acl_get_permset)");
-	result = -1;
+	result = ACL_ERROR;
 	goto cleanup;
       }
 
       int gp_result = acl_get_perm(permset, ACL_EXECUTE);
-      if (gp_result == -1) {
+      if (gp_result == ACL_ERROR) {
 	perror("acl_execute_masked (acl_get_perm)");
-	result = -1;
+	result = ACL_ERROR;
 	goto cleanup;
       }
 
-      if (gp_result == 0) {
+      if (gp_result == ACL_FAILURE) {
 	/* No execute bit set in the mask; execute not allowed. */
-	return 1;
+	return ACL_SUCCESS;
       }
     }
 
@@ -296,39 +380,54 @@ int acl_execute_masked(const char* path) {
 }
 
 
+
+/**
+ * @brief Determine whether @c path is executable (by anyone) or a
+ *   directory.
+ *
+ * This is used as part of the heuristic to determine whether or not
+ * we should mask the execute bit when inheriting an ACL. If @c path
+ * is a directory, the answer is a clear-cut yes. This behavior is
+ * modeled after the capital 'X' perms of setfacl.
+ *
+ * If @c path is a file, we check the @a effective permissions,
+ * contrary to what setfacl does.
+ *
+ * @param path
+ *   The path to check.
+ *
+ * @return
+ *   - @c ACL_SUCCESS - @c path is a directory, or someone has effective
+       execute permissions.
+ *   - @c ACL_FAILURE - @c path is a regular file and nobody can execute
+       it.
+ *   - @c ACL_ERROR - Unexpected library error.
+ */
 int any_can_execute_or_dir(const char* path) {
-  /* If the given path is a directory, returns 1. Otherwise, returns 1
-   * if any ACL entry has EFFECTIVE execute access, 0 if none do, and
-   * -1 on error.
-   *
-   * This is meant to somewhat mimic setfacl's handling of the capital
-   * 'X' perm, which allows execute access if the target is a
-   * directory or someone can already execute it. We differ in that we
-   * check the effective execute rather than just the execute bits.
-   */
 
   if (is_directory(path)) {
     /* That was easy... */
-    return 1;
+    return ACL_SUCCESS;
   }
 
   acl_t acl = acl_get_file(path, ACL_TYPE_ACCESS);
 
   if (acl == (acl_t)NULL) {
-    return 0;
+    perror("any_can_execute_or_dir (acl_get_file)");
+    return ACL_ERROR;
   }
 
   /* Our return value. */
-  int result = 0;
+  int result = ACL_FAILURE;
 
   if (acl_is_minimal(&acl)) {
     mode_t mode = get_mode(path);
     if (mode & (S_IXUSR | S_IXOTH | S_IXGRP)) {
-      result = 1;
+      result = ACL_SUCCESS;
       goto cleanup;
     }
     else {
-      result = 0;
+      result = ACL_FAILURE;
       goto cleanup;
     }
   }
@@ -336,27 +435,44 @@ int any_can_execute_or_dir(const char* path) {
   acl_entry_t entry;
   int ge_result = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
 
-  while (ge_result == 1) {
+  while (ge_result == ACL_SUCCESS) {
+    /* The first thing we do is check to see if this is a mask
+       entry. If it is, we skip it entirely. */
+    acl_tag_t tag = ACL_UNDEFINED_TAG;
+    int tag_result = acl_get_tag_type(entry, &tag);
+
+    if (tag_result == ACL_ERROR) {
+      perror("any_can_execute_or_dir (acl_get_tag_type)");
+      result = ACL_ERROR;
+      goto cleanup;
+    }
+
+    if (tag == ACL_MASK) {
+      ge_result = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
+      continue;
+    }
+
+    /* Ok, so it's not a mask entry. Check the execute perms. */
     acl_permset_t permset;
 
     int ps_result = acl_get_permset(entry, &permset);
-    if (ps_result == -1) {
+    if (ps_result == ACL_ERROR) {
       perror("any_can_execute_or_dir (acl_get_permset)");
-      result = -1;
+      result = ACL_ERROR;
       goto cleanup;
     }
 
     int gp_result = acl_get_perm(permset, ACL_EXECUTE);
-    if (gp_result == -1) {
+    if (gp_result == ACL_ERROR) {
       perror("any_can_execute_or_dir (acl_get_perm)");
-      result = -1;
+      result = ACL_ERROR;
       goto cleanup;
     }
 
-    if (gp_result == 1) {
-      /* Only return one if this execute bit is not masked. */
-      if (acl_execute_masked(path) != 1) {
-	result = 1;
+    if (gp_result == ACL_SUCCESS) {
+      /* Only return ACL_SUCCESS if this execute bit is not masked. */
+      if (acl_execute_masked(path) != ACL_SUCCESS) {
+	result = ACL_SUCCESS;
 	goto cleanup;
       }
     }
@@ -364,9 +480,9 @@ int any_can_execute_or_dir(const char* path) {
     ge_result = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
   }
 
-  if (ge_result == -1) {
+  if (ge_result == ACL_ERROR) {
     perror("any_can_execute_or_dir (acl_get_entry)");
-    result = -1;
+    result = ACL_ERROR;
     goto cleanup;
   }
 
@@ -376,27 +492,43 @@ int any_can_execute_or_dir(const char* path) {
 }
 
 
+
+/**
+ * @brief Inherit the default ACL from @c parent to @c path.
+ *
+ * The @c parent parameter does not necessarily need to be the parent
+ * of @c path, although that will usually be the case. This overwrites
+ * any existing default ACL on @c path.
+ *
+ * @param parent
+ *   The parent directory whose ACL we want to inherit.
+ *
+ * @param path
+ *   The target directory whose ACL we wish to overwrite (or create).
+ *
+ * @return
+ *   - @c ACL_SUCCESS - The default ACL was inherited successfully.
+ *   - @c ACL_FAILURE - Either @c parent or @c path is not a directory.
+ *   - @c ACL_ERROR - Unexpected library error.
+ */
 int inherit_default_acl(const char* path, const char* parent) {
-  /* Inherit the default ACL from parent to path. This overwrites any
-   * existing default ACL. Returns 1 for success, 0 for failure, and
-   * -1 on error.
-   */
 
   /* Our return value. */
-  int result = 1;
+  int result = ACL_SUCCESS;
 
   if (path == NULL) {
     errno = ENOENT;
-    return -1;
+    return ACL_ERROR;
   }
 
   if (!is_directory(path) || !is_directory(parent)) {
-    return 0;
+    return ACL_FAILURE;
   }
 
   acl_t parent_acl = acl_get_file(parent, ACL_TYPE_DEFAULT);
   if (parent_acl == (acl_t)NULL) {
-    return 0;
+    perror("inherit_default_acl (acl_get_file)");
+    return ACL_ERROR;
   }
 
   acl_t path_acl = acl_dup(parent_acl);
@@ -404,13 +536,13 @@ int inherit_default_acl(const char* path, const char* parent) {
   if (path_acl == (acl_t)NULL) {
     perror("inherit_default_acl (acl_dup)");
     acl_free(parent_acl);
-    return -1;
+    return ACL_ERROR;
   }
 
   int sf_result = acl_set_file(path, ACL_TYPE_DEFAULT, path_acl);
   if (sf_result == -1) {
     perror("inherit_default_acl (acl_set_file)");
-    result = -1;
+    result = ACL_ERROR;
     goto cleanup;
   }
 
@@ -420,33 +552,43 @@ int inherit_default_acl(const char* path, const char* parent) {
 }
 
 
+
+/**
+ * @brief Remove @c ACL_USER, @c ACL_GROUP, and @c ACL_MASK entries
+ *   from the given path.
+ *
+ * @param path
+ *   The path whose ACLs we want to wipe.
+ *
+ * @return
+ *   - @c ACL_SUCCESS - The ACLs were wiped successfully, or none
+ *     existed in the first place.
+ *   - @c ACL_ERROR - Unexpected library error.
+ */
 int wipe_acls(const char* path) {
-  /* Remove ACL_USER, ACL_GROUP, and ACL_MASK entries from
-     path. Returns 1 for success, 0 for failure, and -1 on error. */
 
   if (path == NULL) {
     errno = ENOENT;
-    return -1;
+    return ACL_ERROR;
   }
 
-  /* Finally, remove individual named/mask entries. */
   acl_t acl = acl_get_file(path, ACL_TYPE_ACCESS);
   if (acl == (acl_t)NULL) {
     perror("wipe_acls (acl_get_file)");
-    return -1;
+    return ACL_ERROR;
   }
 
   /* Our return value. */
-  int result = 1;
+  int result = ACL_SUCCESS;
 
   acl_entry_t entry;
   int ge_result = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
 
-  while (ge_result == 1) {
+  while (ge_result == ACL_SUCCESS) {
     int d_result = acl_delete_entry(acl, entry);
-    if (d_result == -1) {
+    if (d_result == ACL_ERROR) {
       perror("wipe_acls (acl_delete_entry)");
-      result = -1;
+      result = ACL_ERROR;
       goto cleanup;
     }
 
@@ -455,16 +597,16 @@ int wipe_acls(const char* path) {
 
   /* Catches the first acl_get_entry as well as the ones at the end of
      the loop. */
-  if (ge_result == -1) {
+  if (ge_result == ACL_ERROR) {
     perror("wipe_acls (acl_get_entry)");
-    result = -1;
+    result = ACL_ERROR;
     goto cleanup;
   }
 
   int sf_result = acl_set_file(path, ACL_TYPE_ACCESS, acl);
-  if (sf_result == -1) {
+  if (sf_result == ACL_ERROR) {
     perror("wipe_acls (acl_set_file)");
-    result = -1;
+    result = ACL_ERROR;
     goto cleanup;
   }
 
@@ -474,18 +616,33 @@ int wipe_acls(const char* path) {
 }
 
 
-int apply_default_acl(const char* path) {
-  /* Really apply the default ACL by looping through it. Returns one
-   * for success, zero for failure (i.e. no ACL), and -1 on unexpected
-   * errors.
 
-   */
+/**
+ * @brief Apply parent default ACL to a path.
+ *
+ * This overwrites any existing ACLs on @c path.
+ *
+ * @param path
+ *   The path whose ACL we would like to reset to its default.
+ *
+ * @param no_exec_mask
+ *   The value (either true or false) of the --no-exec-mask flag.
+ *
+ * @return
+ *   - @c ACL_SUCCESS - The parent default ACL was inherited successfully.
+ *   - @c ACL_FAILURE - The target path is not a regular file/directory,
+ *     or the parent of @c path is not a directory.
+ *   - @c ACL_ERROR - Unexpected library error.
+ */
+int apply_default_acl(const char* path, bool no_exec_mask) {
+
   if (path == NULL) {
-    return 0;
+    errno = ENOENT;
+    return ACL_ERROR;
   }
 
   if (!is_regular_file(path) && !is_directory(path)) {
-    return 0;
+    return ACL_FAILURE;
   }
 
   /* dirname mangles its argument */
@@ -496,7 +653,7 @@ int apply_default_acl(const char* path) {
   char* parent = dirname(path_copy);
   if (!is_directory(parent)) {
     /* Make sure dirname() did what we think it did. */
-    return 0;
+    return ACL_FAILURE;
   }
 
   /* Default to not masking the exec bit; i.e. applying the default
@@ -507,10 +664,11 @@ int apply_default_acl(const char* path) {
   if (!no_exec_mask) {
     int ace_result = any_can_execute_or_dir(path);
 
-    if (ace_result == -1) {
-    perror("apply_default_acl (any_can_execute_or_dir)");
-    return -1;
-  }
+    if (ace_result == ACL_ERROR) {
+      perror("apply_default_acl (any_can_execute_or_dir)");
+      return ACL_ERROR;
+    }
+
     allow_exec = (bool)ace_result;
   }
 
@@ -518,16 +676,16 @@ int apply_default_acl(const char* path) {
 
   if (defacl == (acl_t)NULL) {
     perror("apply_default_acl (acl_get_file)");
-    return -1;
+    return ACL_ERROR;
   }
 
   /* Our return value. */
-  int result = 1;
+  int result = ACL_SUCCESS;
 
   int wipe_result = wipe_acls(path);
-  if (wipe_result == -1) {
+  if (wipe_result == ACL_ERROR) {
     perror("apply_default_acl (wipe_acls)");
-    result = -1;
+    result = ACL_ERROR;
     goto cleanup;
   }
 
@@ -536,27 +694,27 @@ int apply_default_acl(const char* path) {
   acl_t acl = acl_get_file(path, ACL_TYPE_ACCESS);
   if (acl == (acl_t)NULL) {
     perror("apply_default_acl (acl_get_file)");
-    return -1;
+    return ACL_ERROR;
   }
 
   /* If it's a directory, inherit the parent's default. */
   int inherit_result = inherit_default_acl(path, parent);
-  if (inherit_result == -1) {
+  if (inherit_result == ACL_ERROR) {
     perror("apply_default_acl (inherit_acls)");
-    result = -1;
+    result = ACL_ERROR;
     goto cleanup;
   }
 
   acl_entry_t entry;
   int ge_result = acl_get_entry(defacl, ACL_FIRST_ENTRY, &entry);
 
-  while (ge_result == 1) {
+  while (ge_result == ACL_SUCCESS) {
     acl_tag_t tag = ACL_UNDEFINED_TAG;
     int tag_result = acl_get_tag_type(entry, &tag);
 
-    if (tag_result == -1) {
+    if (tag_result == ACL_ERROR) {
        perror("apply_default_acl (acl_get_tag_type)");
-       result = -1;
+       result = ACL_ERROR;
        goto cleanup;
     }
 
@@ -564,9 +722,9 @@ int apply_default_acl(const char* path) {
     /* We've got an entry/tag from the default ACL. Get its permset. */
     acl_permset_t permset;
     int ps_result = acl_get_permset(entry, &permset);
-    if (ps_result == -1) {
+    if (ps_result == ACL_ERROR) {
       perror("apply_default_acl (acl_get_permset)");
-      result = -1;
+      result = ACL_ERROR;
       goto cleanup;
     }
 
@@ -581,16 +739,16 @@ int apply_default_acl(const char* path) {
 	   minimal ACLs) or acl_other entries, so if execute should be
 	   masked, we have to do it manually. */
 	int d_result = acl_delete_perm(permset, ACL_EXECUTE);
-	if (d_result == -1) {
+	if (d_result == ACL_ERROR) {
 	  perror("apply_default_acl (acl_delete_perm)");
-	  result = -1;
+	  result = ACL_ERROR;
 	  goto cleanup;
 	}
 
 	int sp_result = acl_set_permset(entry, permset);
-	if (sp_result == -1) {
+	if (sp_result == ACL_ERROR) {
 	  perror("apply_default_acl (acl_set_permset)");
-	  result = -1;
+	  result = ACL_ERROR;
 	  goto cleanup;
 	}
       }
@@ -598,9 +756,9 @@ int apply_default_acl(const char* path) {
 
     /* Finally, add the permset to the access ACL. */
     int set_result = acl_set_entry(&acl, entry);
-    if (set_result == -1) {
+    if (set_result == ACL_ERROR) {
       perror("apply_default_acl (acl_set_entry)");
-      result = -1;
+      result = ACL_ERROR;
       goto cleanup;
     }
 
@@ -609,16 +767,16 @@ int apply_default_acl(const char* path) {
 
   /* Catches the first acl_get_entry as well as the ones at the end of
      the loop. */
-  if (ge_result == -1) {
+  if (ge_result == ACL_ERROR) {
     perror("apply_default_acl (acl_get_entry)");
-    result = -1;
+    result = ACL_ERROR;
     goto cleanup;
   }
 
   int sf_result = acl_set_file(path, ACL_TYPE_ACCESS, acl);
-  if (sf_result == -1) {
+  if (sf_result == ACL_ERROR) {
     perror("apply_default_acl (acl_set_file)");
-    result = -1;
+    result = ACL_ERROR;
     goto cleanup;
   }
 
@@ -628,10 +786,15 @@ int apply_default_acl(const char* path) {
 }
 
 
+
+/**
+ * @brief Display program usage information.
+ *
+ * @param program_name
+ *   The program name to use in the output.
+ *
+ */
 void usage(char* program_name) {
-  /*
-   * Print usage information.
-   */
   printf("Apply any applicable default ACLs to the given files or "
 	 "directories.\n\n");
   printf("Usage: %s [flags] <target1> [<target2> [ <target3>...]]\n\n",
@@ -645,43 +808,98 @@ void usage(char* program_name) {
 }
 
 
+/**
+ * @brief Wrapper around @c apply_default_acl() for use with @c nftw().
+ *
+ * For parameter information, see the @c nftw man page.
+ *
+ * @return If the ACL was applied to @c target successfully, we return
+ *   @c FTW_CONTINUE to signal to @ nftw() that we should proceed onto
+ *   the next file or directory. Otherwise, we return @c FTW_STOP to
+ *   signal failure.
+ *
+ */
 int apply_default_acl_nftw(const char *target,
 			   const struct stat *s,
 			   int info,
 			   struct FTW *ftw) {
-  /* A wrapper around the apply_default_acl() function for use with
-   * nftw(). We need to adjust the return value so that nftw() doesn't
-   * think we've failed.
-   */
-  bool reapp_result = apply_default_acl(target);
-  if (reapp_result) {
-    return 0;
+
+  bool app_result = apply_default_acl(target, false);
+  if (app_result) {
+    return FTW_CONTINUE;
   }
   else {
-    return 1;
+    return FTW_STOP;
   }
 }
 
 
-bool apply_default_acl_recursive(const char *target) {
-  /* Attempt to apply default ACLs recursively. If target is a
-   * directory, we recurse through its entries. If not, we just
-   * apply the default ACL to target.
-   *
-   * We ignore symlinks for consistency with chmod -r.
-   *
-   */
+
+/**
+ * @brief Wrapper around @c apply_default_acl() for use with @c nftw().
+ *
+ * This is identical to @c apply_default_acl_nftw(), except it passes
+ * @c true to @c apply_default_acl() as its no_exec_mask argument.
+ *
+ */
+int apply_default_acl_nftw_x(const char *target,
+			     const struct stat *s,
+			     int info,
+			     struct FTW *ftw) {
+
+  bool app_result = apply_default_acl(target, true);
+  if (app_result) {
+    return FTW_CONTINUE;
+  }
+  else {
+    return FTW_STOP;
+  }
+}
+
+
+
+/**
+ * @brief Recursive version of @c apply_default_acl().
+ *
+ * If @c target is a directory, we use @c nftw() to call @c
+ * apply_default_acl() recursively on all of its children. Otherwise,
+ * we just delegate to @c apply_default_acl().
+ *
+ * We ignore symlinks for consistency with chmod -r.
+ *
+ * @param target
+ *   The root (path) of the recursive application.
+ *
+ * @param no_exec_mask
+ *   The value (either true or false) of the --no-exec-mask flag.
+ *
+ * @return
+ *   If @c target is not a directory, we return the result of
+ *   calling @c apply_default_acl() on @c target. Otherwise, we convert
+ *   the return value of @c nftw(). If @c nftw() succeeds (returns 0),
+ *   then we return @c true. Otherwise, we return @c false.
+ *   \n\n
+ *   If there is an error, it will be reported via @c perror, but
+ *   we still return @c false.
+ */
+bool apply_default_acl_recursive(const char *target, bool no_exec_mask) {
+
   if (!is_directory(target)) {
-    return apply_default_acl(target);
+    return apply_default_acl(target, no_exec_mask);
   }
 
   int max_levels = 256;
   int flags = FTW_PHYS; /* Don't follow links. */
 
-  int nftw_result = nftw(target,
-			 apply_default_acl_nftw,
-			 max_levels,
-			 flags);
+  /* There are two separate functions that could be passed to
+     nftw(). One passes no_exec_mask = true to apply_default_acl(),
+     and the other passes no_exec_mask = false. Since the function we
+     pass to nftw() cannot have parameters, we have to create separate
+     options and make the decision here. */
+  int (*fn)(const char *, const struct stat *, int, struct FTW *) = NULL;
+  fn = no_exec_mask ? apply_default_acl_nftw_x : apply_default_acl_nftw;
+
+  int nftw_result = nftw(target, fn, max_levels, flags);
 
   if (nftw_result == 0) {
     /* Success */
@@ -700,17 +918,24 @@ bool apply_default_acl_recursive(const char *target) {
 }
 
 
+
+/**
+ * @brief Call apply_default_acl (possibly recursively) on each
+ * command-line argument.
+ *
+ * @return Either @c EXIT_FAILURE or @c EXIT_SUCCESS. If everything
+ *   goes as expected, we return @c EXIT_SUCCESS. Otherwise, we return
+ *   @c EXIT_FAILURE.
+ */
 int main(int argc, char* argv[]) {
-  /*
-   * Call apply_default_acl on each command-line argument.
-   */
+
   if (argc < 2) {
     usage(argv[0]);
     return EXIT_FAILURE;
   }
 
   bool recursive = false;
-  /* bool no_exec_mask is declared static/global */
+  bool no_exec_mask = false;
 
   struct option long_options[] = {
     /* These options set a flag. */
@@ -747,11 +972,11 @@ int main(int argc, char* argv[]) {
     bool reapp_result = false;
 
     if (recursive) {
-      reapp_result = apply_default_acl_recursive(target);
+      reapp_result = apply_default_acl_recursive(target, no_exec_mask);
     }
     else {
       /* It's either normal file, or we're not operating recursively. */
-      reapp_result = apply_default_acl(target);
+      reapp_result = apply_default_acl(target, no_exec_mask);
     }
 
     if (!reapp_result) {