lib/path.c

   1 /*
   2  * Simple functions to access files. Paths can be globally prefixed to read
   3  * data from an alternative source (e.g. a /proc dump for regression tests).
   4  *
   5  * Copyright (C) 2008 Cai Qian <qcai@redhat.com>
   6  * Copyright (C) 2008-2012 Karel Zak <kzak@redhat.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it would be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22
  23 #include <stdarg.h>
  24 #include <string.h>
  25 #include <unistd.h>
  26 #include <stdio.h>
  27 #include <inttypes.h>
  28 #include <errno.h>
  29
  30 #include "all-io.h"
  31 #include "path.h"
  32 #include "nls.h"
  33 #include "c.h"
  34
  35 static size_t prefixlen;
  36 static char pathbuf[PATH_MAX];
  37
  38 static const char *
  39 path_vcreate(const char *path, va_list ap)
  40 {
  41         if (prefixlen)
  42                 vsnprintf(pathbuf + prefixlen,
  43                           sizeof(pathbuf) - prefixlen, path, ap);
  44         else
  45                 vsnprintf(pathbuf, sizeof(pathbuf), path, ap);
  46         return pathbuf;
  47 }
  48
  49 char *
  50 path_strdup(const char *path, ...)
  51 {
  52         const char *p;
  53         va_list ap;
  54
  55         va_start(ap, path);
  56         p = path_vcreate(path, ap);
  57         va_end(ap);
  58
  59         return p ? strdup(p) : NULL;
  60 }
  61
  62 static FILE *
  63 path_vfopen(const char *mode, int exit_on_error, const char *path, va_list ap)
  64 {
  65         FILE *f;
  66         const char *p = path_vcreate(path, ap);
  67
  68         f = fopen(p, mode);
  69         if (!f && exit_on_error)
  70                 err(EXIT_FAILURE, _("cannot open %s"), p);
  71         return f;
  72 }
  73
  74 static int
  75 path_vopen(int flags, const char *path, va_list ap)
  76 {
  77         int fd;
  78         const char *p = path_vcreate(path, ap);
  79
  80         fd = open(p, flags);
  81         if (fd == -1)
  82                 err(EXIT_FAILURE, _("cannot open %s"), p);
  83         return fd;
  84 }
  85
  86 FILE *
  87 path_fopen(const char *mode, int exit_on_error, const char *path, ...)
  88 {
  89         FILE *fd;
  90         va_list ap;
  91
  92         va_start(ap, path);
  93         fd = path_vfopen(mode, exit_on_error, path, ap);
  94         va_end(ap);
  95
  96         return fd;
  97 }
  98
  99 void
 100 path_read_str(char *result, size_t len, const char *path, ...)
 101 {
 102         FILE *fd;
 103         va_list ap;
 104
 105         va_start(ap, path);
 106         fd = path_vfopen("r" UL_CLOEXECSTR, 1, path, ap);
 107         va_end(ap);
 108
 109         if (!fgets(result, len, fd))
 110                 err(EXIT_FAILURE, _("cannot read %s"), pathbuf);
 111         fclose(fd);
 112
 113         len = strlen(result);
 114         if (result[len - 1] == '\n')
 115                 result[len - 1] = '\0';
 116 }
 117
 118 int
 119 path_read_s32(const char *path, ...)
 120 {
 121         FILE *fd;
 122         va_list ap;
 123         int result;
 124
 125         va_start(ap, path);
 126         fd = path_vfopen("r" UL_CLOEXECSTR, 1, path, ap);
 127         va_end(ap);
 128
 129         if (fscanf(fd, "%d", &result) != 1) {
 130                 if (ferror(fd))
 131                         err(EXIT_FAILURE, _("cannot read %s"), pathbuf);
 132                 else
 133                         errx(EXIT_FAILURE, _("parse error: %s"), pathbuf);
 134         }
 135         fclose(fd);
 136         return result;
 137 }
 138
 139 uint64_t
 140 path_read_u64(const char *path, ...)
 141 {
 142         FILE *fd;
 143         va_list ap;
 144         uint64_t result;
 145
 146         va_start(ap, path);
 147         fd = path_vfopen("r", 1, path, ap);
 148         va_end(ap);
 149
 150         if (fscanf(fd, "%"SCNu64, &result) != 1) {
 151                 if (ferror(fd))
 152                         err(EXIT_FAILURE, _("cannot read %s"), pathbuf);
 153                 else
 154                         errx(EXIT_FAILURE, _("parse error: %s"), pathbuf);
 155         }
 156         fclose(fd);
 157         return result;
 158 }
 159
 160 int
 161 path_write_str(const char *str, const char *path, ...)
 162 {
 163         int fd, result;
 164         va_list ap;
 165
 166         va_start(ap, path);
 167         fd = path_vopen(O_WRONLY|O_CLOEXEC, path, ap);
 168         va_end(ap);
 169         result = write_all(fd, str, strlen(str));
 170         close(fd);
 171         return result;
 172 }
 173
 174 int
 175 path_exist(const char *path, ...)
 176 {
 177         va_list ap;
 178         const char *p;
 179
 180         va_start(ap, path);
 181         p = path_vcreate(path, ap);
 182         va_end(ap);
 183
 184         return access(p, F_OK) == 0;
 185 }
 186
 187 #ifdef HAVE_CPU_SET_T
 188
 189 static cpu_set_t *
 190 path_cpuparse(int maxcpus, int islist, const char *path, va_list ap)
 191 {
 192         FILE *fd;
 193         cpu_set_t *set;
 194         size_t setsize, len = maxcpus * 7;
 195         char buf[len];
 196
 197         fd = path_vfopen("r" UL_CLOEXECSTR, 1, path, ap);
 198
 199         if (!fgets(buf, len, fd))
 200                 err(EXIT_FAILURE, _("cannot read %s"), pathbuf);
 201         fclose(fd);
 202
 203         len = strlen(buf);
 204         if (buf[len - 1] == '\n')
 205                 buf[len - 1] = '\0';
 206
 207         set = cpuset_alloc(maxcpus, &setsize, NULL);
 208         if (!set)
 209                 err(EXIT_FAILURE, _("failed to callocate cpu set"));
 210
 211         if (islist) {
 212                 if (cpulist_parse(buf, set, setsize, 0))
 213                         errx(EXIT_FAILURE, _("failed to parse CPU list %s"), buf);
 214         } else {
 215                 if (cpumask_parse(buf, set, setsize))
 216                         errx(EXIT_FAILURE, _("failed to parse CPU mask %s"), buf);
 217         }
 218         return set;
 219 }
 220
 221 cpu_set_t *
 222 path_read_cpuset(int maxcpus, const char *path, ...)
 223 {
 224         va_list ap;
 225         cpu_set_t *set;
 226
 227         va_start(ap, path);
 228         set = path_cpuparse(maxcpus, 0, path, ap);
 229         va_end(ap);
 230
 231         return set;
 232 }
 233
 234 cpu_set_t *
 235 path_read_cpulist(int maxcpus, const char *path, ...)
 236 {
 237         va_list ap;
 238         cpu_set_t *set;
 239
 240         va_start(ap, path);
 241         set = path_cpuparse(maxcpus, 1, path, ap);
 242         va_end(ap);
 243
 244         return set;
 245 }
 246
 247 #endif /* HAVE_CPU_SET_T */
 248
 249 void
 250 path_set_prefix(const char *prefix)
 251 {
 252         prefixlen = strlen(prefix);
 253         strncpy(pathbuf, prefix, sizeof(pathbuf));
 254         pathbuf[sizeof(pathbuf) - 1] = '\0';
 255 }