panel-plugin/hdaps.c

   1 #ifdef HAVE_CONFIG_H
   2 #include <config.h>
   3 #endif
   4
   5 #include <dirent.h>
   6 #include <sys/types.h>
   7 #include <errno.h>
   8 #include <fcntl.h>
   9 #include <stdio.h>
  10 #include <string.h>
  11 #include "hdaps.h"
  12
  13 /* The most space we expect to need when reading in
  14    a file using these hdaps functions. To exceed 32
  15    bytes worth of content in unload_heads you'd have
  16    to throw your laptop hard as a motherfucker. */
  17 #define MAX_FILE_CONTENTS_SIZE 32
  18
  19 /* Where the block device names are located. */
  20 #define SYSFS_BLOCK_DEVICE_DIR "/sys/block/"
  21
  22
  23 static int hdaps_device_exists(const char* device) {
  24   /* Determine whether or not a device (file) exists and has an
  25      unload_heads entry in sysfs. */
  26   char path[FILENAME_MAX];
  27   snprintf(path, FILENAME_MAX, UNLOAD_HEADS_FMT, device);
  28   return (access(path, F_OK) == 0);
  29 }
  30
  31
  32 int get_hdaps_device_list(char list[MAX_HDAPS_DEVICES][FILENAME_MAX]) {
  33   int list_idx = 0;
  34   DIR *dp;
  35   struct dirent *ep;
  36
  37   dp = opendir(SYSFS_BLOCK_DEVICE_DIR);
  38
  39   if (dp != NULL) {
  40     while ((ep = readdir(dp)) && list_idx < MAX_HDAPS_DEVICES) {
  41       /* This next test covers "." and ".." too. */
  42       if (hdaps_device_exists(ep->d_name)) {
  43         strncpy(list[list_idx], ep->d_name, FILENAME_MAX);
  44         list_idx++;
  45       }
  46     }
  47
  48     (void)closedir(dp); /* Explicitly ignore this. */
  49   }
  50
  51   return list_idx;
  52 }
  53
  54
  55 int slurp_file(const char* filename, char* buf, int max_bytes) {
  56   /* This function just reads the contents of filename
  57    * into buf. It is slightly stolen from the hdapsd project.
  58    */
  59
  60   /* Return an error value by default. */
  61   int ret = HDAPS_ERROR;
  62   int fd = open(filename, O_RDONLY);
  63
  64   if (filename == NULL || buf == NULL) {
  65     return ret;
  66   }
  67
  68   if (fd < 0) {
  69     fprintf(stderr, "open(%s): %s\n", filename, strerror(errno));
  70     return fd;
  71   }
  72
  73   ret = read(fd, buf, max_bytes-1);
  74
  75   if (ret < 0) {
  76     fprintf(stderr, "read(%s): %s\n", filename, strerror(errno));
  77   }
  78   else {
  79     buf[ret] = 0; /* Null-terminate buf. */
  80   }
  81
  82   if (close(fd)) {
  83     fprintf(stderr, "close(%s): %s\n", filename, strerror(errno));
  84   }
  85
  86   return ret;
  87 }
  88
  89
  90
  91
  92 int parse_int_from_file(const char* filename) {
  93   /* Read an integer from a file. We expect the file
  94      to contain an integer (although in string form). */
  95
  96   char buf[MAX_FILE_CONTENTS_SIZE];
  97   int ret = slurp_file(filename, buf, sizeof(buf));
  98
  99   if (ret < 0) {
 100     /* Why did we read fewer than 0 bytes? */
 101     return ret;
 102   }
 103   else {
 104     /* If we read more than 0 bytes, hopefully we can
 105        count on atoi to succeed. */
 106     return atoi(buf);
 107   }
 108 }