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         int rc = vsnprintf(
  42                 pathbuf + prefixlen, sizeof(pathbuf) - prefixlen, path, ap);
  43
  44         if (rc < 0)
  45                 return NULL;
  46         if ((size_t)rc >= sizeof(pathbuf)) {
  47                 errno = ENAMETOOLONG;
  48                 return NULL;
  49         }
  50         return pathbuf;
  51 }
  52
  53 const char *
  54 path_get(const char *path, ...)
  55 {
  56         const char *p;
  57         va_list ap;
  58
  59         va_start(ap, path);
  60         p = path_vcreate(path, ap);
  61         va_end(ap);
  62
  63         return p;
  64 }
  65
  66 static FILE *
  67 path_vfopen(const char *mode, int exit_on_error, const char *path, va_list ap)
  68 {
  69         FILE *f;
  70         const char *p = path_vcreate(path, ap);
  71         if (!p)
  72                 goto err;
  73
  74         f = fopen(p, mode);
  75         if (!f)
  76                 goto err;
  77
  78         return f;
  79 err:
  80         if (exit_on_error)
  81                 err(EXIT_FAILURE, _("cannot open %s"), p ? p : "path");
  82         return NULL;
  83 }
  84
  85 static int
  86 path_vopen(int flags, const char *path, va_list ap)
  87 {
  88         int fd;
  89         const char *p = path_vcreate(path, ap);
  90         if (!p)
  91                 goto err;
  92
  93         fd = open(p, flags);
  94         if (fd == -1)
  95                 goto err;
  96
  97         return fd;
  98 err:
  99         err(EXIT_FAILURE, _("cannot open %s"), p ? p : "path");
 100 }
 101
 102 FILE *
 103 path_fopen(const char *mode, int exit_on_error, const char *path, ...)
 104 {
 105         FILE *fd;
 106         va_list ap;
 107
 108         va_start(ap, path);
 109         fd = path_vfopen(mode, exit_on_error, path, ap);
 110         va_end(ap);
 111
 112         return fd;
 113 }
 114
 115 void
 116 path_read_str(char *result, size_t len, const char *path, ...)
 117 {
 118         FILE *fd;
 119         va_list ap;
 120
 121         va_start(ap, path);
 122         fd = path_vfopen("r" UL_CLOEXECSTR, 1, path, ap);
 123         va_end(ap);
 124
 125         if (!fgets(result, len, fd))
 126                 err(EXIT_FAILURE, _("cannot read %s"), pathbuf);
 127         fclose(fd);
 128
 129         len = strlen(result);
 130         if (result[len - 1] == '\n')
 131                 result[len - 1] = '\0';
 132 }
 133
 134 int
 135 path_read_s32(const char *path, ...)
 136 {
 137         FILE *fd;
 138         va_list ap;
 139         int result;
 140
 141         va_start(ap, path);
 142         fd = path_vfopen("r" UL_CLOEXECSTR, 1, path, ap);
 143         va_end(ap);
 144
 145         if (fscanf(fd, "%d", &result) != 1) {
 146                 if (ferror(fd))
 147                         err(EXIT_FAILURE, _("cannot read %s"), pathbuf);
 148                 else
 149                         errx(EXIT_FAILURE, _("parse error: %s"), pathbuf);
 150         }
 151         fclose(fd);
 152         return result;
 153 }
 154
 155 uint64_t
 156 path_read_u64(const char *path, ...)
 157 {
 158         FILE *fd;
 159         va_list ap;
 160         uint64_t result;
 161
 162         va_start(ap, path);
 163         fd = path_vfopen("r", 1, path, ap);
 164         va_end(ap);
 165
 166         if (fscanf(fd, "%"SCNu64, &result) != 1) {
 167                 if (ferror(fd))
 168                         err(EXIT_FAILURE, _("cannot read %s"), pathbuf);
 169                 else
 170                         errx(EXIT_FAILURE, _("parse error: %s"), pathbuf);
 171         }
 172         fclose(fd);
 173         return result;
 174 }
 175
 176 int
 177 path_write_str(const char *str, const char *path, ...)
 178 {
 179         int fd, result;
 180         va_list ap;
 181
 182         va_start(ap, path);
 183         fd = path_vopen(O_WRONLY|O_CLOEXEC, path, ap);
 184         va_end(ap);
 185         result = write_all(fd, str, strlen(str));
 186         close(fd);
 187         return result;
 188 }
 189
 190 int
 191 path_exist(const char *path, ...)
 192 {
 193         va_list ap;
 194         const char *p;
 195
 196         va_start(ap, path);
 197         p = path_vcreate(path, ap);
 198         va_end(ap);
 199
 200         return p && access(p, F_OK) == 0;
 201 }
 202
 203 #ifdef HAVE_CPU_SET_T
 204
 205 static cpu_set_t *
 206 path_cpuparse(int maxcpus, int islist, const char *path, va_list ap)
 207 {
 208         FILE *fd;
 209         cpu_set_t *set;
 210         size_t setsize, len = maxcpus * 7;
 211         char buf[len];
 212
 213         fd = path_vfopen("r" UL_CLOEXECSTR, 1, path, ap);
 214
 215         if (!fgets(buf, len, fd))
 216                 err(EXIT_FAILURE, _("cannot read %s"), pathbuf);
 217         fclose(fd);
 218
 219         len = strlen(buf);
 220         if (buf[len - 1] == '\n')
 221                 buf[len - 1] = '\0';
 222
 223         set = cpuset_alloc(maxcpus, &setsize, NULL);
 224         if (!set)
 225                 err(EXIT_FAILURE, _("failed to callocate cpu set"));
 226
 227         if (islist) {
 228                 if (cpulist_parse(buf, set, setsize, 0))
 229                         errx(EXIT_FAILURE, _("failed to parse CPU list %s"), buf);
 230         } else {
 231                 if (cpumask_parse(buf, set, setsize))
 232                         errx(EXIT_FAILURE, _("failed to parse CPU mask %s"), buf);
 233         }
 234         return set;
 235 }
 236
 237 cpu_set_t *
 238 path_read_cpuset(int maxcpus, const char *path, ...)
 239 {
 240         va_list ap;
 241         cpu_set_t *set;
 242
 243         va_start(ap, path);
 244         set = path_cpuparse(maxcpus, 0, path, ap);
 245         va_end(ap);
 246
 247         return set;
 248 }
 249
 250 cpu_set_t *
 251 path_read_cpulist(int maxcpus, const char *path, ...)
 252 {
 253         va_list ap;
 254         cpu_set_t *set;
 255
 256         va_start(ap, path);
 257         set = path_cpuparse(maxcpus, 1, path, ap);
 258         va_end(ap);
 259
 260         return set;
 261 }
 262
 263 int
 264 path_set_prefix(const char *prefix)
 265 {
 266         size_t len = strlen(prefix);
 267
 268         if (len >= sizeof(pathbuf) - 1) {
 269                 errno = ENAMETOOLONG;
 270                 return -1;
 271         }
 272         prefixlen = len;
 273         strcpy(pathbuf, prefix);
 274         return 0;
 275 }
 276
 277 #endif /* HAVE_CPU_SET_T */