src/misc/mntent.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <mntent.h>
   4 #include <errno.h>
   5 #include <limits.h>
   6
   7 static char *internal_buf;
   8 static size_t internal_bufsize;
   9
  10 #define SENTINEL (char *)&internal_buf
  11
  12 FILE *setmntent(const char *name, const char *mode)
  13 {
  14         return fopen(name, mode);
  15 }
  16
  17 int endmntent(FILE *f)
  18 {
  19         if (f) fclose(f);
  20         return 1;
  21 }
  22
  23 static char *unescape_ent(char *beg)
  24 {
  25         char *dest = beg;
  26         const char *src = beg;
  27         while (*src) {
  28                 const char *val;
  29                 unsigned char cval = 0;
  30                 if (*src != '\\') {
  31                         *dest++ = *src++;
  32                         continue;
  33                 }
  34                 if (src[1] == '\\') {
  35                         ++src;
  36                         *dest++ = *src++;
  37                         continue;
  38                 }
  39                 val = src + 1;
  40                 for (int i = 0; i < 3; ++i) {
  41                         if (*val >= '0' && *val <= '7') {
  42                                 cval <<= 3;
  43                                 cval += *val++ - '0';
  44                         } else {
  45                                 break;
  46                         }
  47                 }
  48                 if (cval) {
  49                         *dest++ = cval;
  50                         src = val;
  51                 } else {
  52                         *dest++ = *src++;
  53                 }
  54         }
  55         *dest = 0;
  56         return beg;
  57 }
  58
  59 struct mntent *getmntent_r(FILE *f, struct mntent *mnt, char *linebuf, int buflen)
  60 {
  61         int n[8], use_internal = (linebuf == SENTINEL);
  62         size_t len, i;
  63
  64         mnt->mnt_freq = 0;
  65         mnt->mnt_passno = 0;
  66
  67         do {
  68                 if (use_internal) {
  69                         getline(&internal_buf, &internal_bufsize, f);
  70                         linebuf = internal_buf;
  71                 } else {
  72                         fgets(linebuf, buflen, f);
  73                 }
  74                 if (feof(f) || ferror(f)) return 0;
  75                 if (!strchr(linebuf, '\n')) {
  76                         fscanf(f, "%*[^\n]%*[\n]");
  77                         errno = ERANGE;
  78                         return 0;
  79                 }
  80
  81                 len = strlen(linebuf);
  82                 if (len > INT_MAX) continue;
  83                 for (i = 0; i < sizeof n / sizeof *n; i++) n[i] = len;
  84                 sscanf(linebuf, " %n%*[^ \t]%n %n%*[^ \t]%n %n%*[^ \t]%n %n%*[^ \t]%n %d %d",
  85                         n, n+1, n+2, n+3, n+4, n+5, n+6, n+7,
  86                         &mnt->mnt_freq, &mnt->mnt_passno);
  87         } while (linebuf[n[0]] == '#' || n[1]==len);
  88
  89         linebuf[n[1]] = 0;
  90         linebuf[n[3]] = 0;
  91         linebuf[n[5]] = 0;
  92         linebuf[n[7]] = 0;
  93
  94         mnt->mnt_fsname = unescape_ent(linebuf+n[0]);
  95         mnt->mnt_dir = unescape_ent(linebuf+n[2]);
  96         mnt->mnt_type = unescape_ent(linebuf+n[4]);
  97         mnt->mnt_opts = unescape_ent(linebuf+n[6]);
  98
  99         return mnt;
 100 }
 101
 102 struct mntent *getmntent(FILE *f)
 103 {
 104         static struct mntent mnt;
 105         return getmntent_r(f, &mnt, SENTINEL, 0);
 106 }
 107
 108 int addmntent(FILE *f, const struct mntent *mnt)
 109 {
 110         if (fseek(f, 0, SEEK_END)) return 1;
 111         return fprintf(f, "%s\t%s\t%s\t%s\t%d\t%d\n",
 112                 mnt->mnt_fsname, mnt->mnt_dir, mnt->mnt_type, mnt->mnt_opts,
 113                 mnt->mnt_freq, mnt->mnt_passno) < 0;
 114 }
 115
 116 char *hasmntopt(const struct mntent *mnt, const char *opt)
 117 {
 118         return strstr(mnt->mnt_opts, opt);
 119 }