libfstools/partname.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2
   3 #include "common.h"
   4
   5 #define BUFLEN 64
   6
   7 const char *const block_dir_name = "/sys/class/block";
   8
   9 struct devpath {
  10         char prefix[5];
  11         char device[11];
  12 };
  13
  14 struct partname_volume {
  15         struct volume v;
  16         union {
  17                 char devpathstr[16];
  18                 struct devpath devpath;
  19         } dev;
  20
  21         union {
  22                 char devpathstr[16];
  23                 struct devpath devpath;
  24         } parent_dev;
  25 };
  26
  27 static struct driver partname_driver;
  28
  29 static int partname_volume_identify(struct volume *v)
  30 {
  31         struct partname_volume *p = container_of(v, struct partname_volume, v);
  32         int ret = FS_NONE;
  33         FILE *f;
  34
  35         f = fopen(p->dev.devpathstr, "r");
  36         if (!f)
  37                 return ret;
  38
  39         ret = block_file_identify(f, 0);
  40
  41         fclose(f);
  42
  43         return ret;
  44 }
  45
  46 static int partname_volume_init(struct volume *v)
  47 {
  48         struct partname_volume *p = container_of(v, struct partname_volume, v);
  49         char voldir[BUFLEN];
  50         unsigned int volsize;
  51
  52         snprintf(voldir, sizeof(voldir), "%s/%s", block_dir_name, p->dev.devpath.device);
  53
  54         if (read_uint_from_file(voldir, "size", &volsize))
  55                 return -1;
  56
  57         v->type = BLOCKDEV;
  58         v->size = volsize << 9; /* size is returned in sectors of 512 bytes */
  59         v->blk = p->dev.devpathstr;
  60
  61         return block_volume_format(v, 0, p->parent_dev.devpathstr);
  62 }
  63
  64 /* from procd/utils.c -> should go to libubox */
  65 static char* get_cmdline_val(const char* name, char* out, int len)
  66 {
  67         char line[1024], *c, *sptr;
  68         int fd = open("/proc/cmdline", O_RDONLY);
  69         ssize_t r = read(fd, line, sizeof(line) - 1);
  70         close(fd);
  71
  72         if (r <= 0)
  73                 return NULL;
  74
  75         line[r] = 0;
  76
  77         for (c = strtok_r(line, " \t\n", &sptr); c;
  78                         c = strtok_r(NULL, " \t\n", &sptr)) {
  79                 char *sep = strchr(c, '=');
  80                 if (sep == NULL)
  81                         continue;
  82
  83                 ssize_t klen = sep - c;
  84                 if (strncmp(name, c, klen) || name[klen] != 0)
  85                         continue;
  86
  87                 strncpy(out, &sep[1], len);
  88                 out[len-1] = '\0';
  89                 return out;
  90         }
  91
  92         return NULL;
  93 }
  94
  95 static char *rootdevname(char *devpath) {
  96         int l;
  97
  98         l = strlen(devpath) - 1;
  99
 100         /* strip partition suffix from root=/dev/... string */
 101         while (l > 0 && (devpath[l] >= '0' && devpath[l] <= '9'))
 102                 --l;
 103
 104         if (devpath[l] != 'p')
 105                 ++l;
 106
 107         devpath[l] = '\0';
 108
 109         return basename(devpath);
 110 }
 111
 112 static struct volume *partname_volume_find(char *name)
 113 {
 114         struct partname_volume *p;
 115         char volnamegstr[BUFLEN];
 116         char namebuf[BUFLEN];
 117         char rootparam[BUFLEN];
 118         char *rootdev = NULL, *devname, *tmp;
 119         int j;
 120         bool found = false;
 121         glob_t gl;
 122
 123         if (get_cmdline_val("fstools_ignore_partname", rootparam, sizeof(rootparam))) {
 124                 if (!strcmp("1", rootparam))
 125                         return NULL;
 126         }
 127
 128         if (get_cmdline_val("root", rootparam, sizeof(rootparam))) {
 129                 rootdev = rootdevname(rootparam);
 130                 /* find partition on same device as rootfs */
 131                 snprintf(volnamegstr, sizeof(volnamegstr), "%s/%s/*/name", block_dir_name, rootdev);
 132         } else {
 133                 /* no 'root=' kernel cmdline parameter, find on any block device */
 134                 snprintf(volnamegstr, sizeof(volnamegstr), "%s/*/name", block_dir_name);
 135         }
 136
 137         if (!glob(volnamegstr, GLOB_NOESCAPE, NULL, &gl))
 138                 for (j = 0; j < gl.gl_pathc; j++) {
 139                         if (!read_string_from_file("", gl.gl_pathv[j], namebuf, sizeof(namebuf)))
 140                                 continue;
 141                         if (!strncmp(namebuf, name, sizeof(namebuf))) {
 142                                 found = 1;
 143                                 break;
 144                         }
 145                 }
 146
 147         if (!found)
 148                 return NULL;
 149
 150         devname = gl.gl_pathv[j];
 151         tmp = strrchr(devname, '/');
 152         *tmp = '\0';
 153         devname = strrchr(devname, '/') + 1;
 154
 155         p = calloc(1, sizeof(*p));
 156         memcpy(p->dev.devpath.prefix, "/dev/", sizeof(p->dev.devpath.prefix));
 157         strncpy(p->dev.devpath.device, devname, sizeof(p->dev.devpath.device) - 1);
 158         p->dev.devpath.device[sizeof(p->dev.devpath.device)-1] = '\0';
 159
 160         memcpy(p->parent_dev.devpath.prefix, "/dev/", sizeof(p->parent_dev.devpath.prefix));
 161         if (rootdev)
 162                 strncpy(p->parent_dev.devpath.device, rootdev, sizeof(p->parent_dev.devpath.device) - 1);
 163         else
 164                 strncpy(p->parent_dev.devpath.device, rootdevname(devname), sizeof(p->parent_dev.devpath.device) - 1);
 165
 166         p->parent_dev.devpath.device[sizeof(p->parent_dev.devpath.device)-1] = '\0';
 167
 168         p->v.drv = &partname_driver;
 169         p->v.blk = p->dev.devpathstr;
 170         p->v.name = name;
 171
 172         return &p->v;
 173 }
 174
 175 static struct driver partname_driver = {
 176         .name = "partname",
 177         .find = partname_volume_find,
 178         .init = partname_volume_init,
 179         .identify = partname_volume_identify,
 180 };
 181
 182 DRIVER(partname_driver);