fstools: add partname volume driver

[project/fstools.git] / libfstools / partname.c

diff --git a/libfstools/partname.c b/libfstools/partname.c
new file mode 100644 (file)
index 0000000..9073a0d
--- /dev/null
+++ b/libfstools/partname.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "common.h"
+
+#define BUFLEN 64
+
+const char *const block_dir_name = "/sys/class/block";
+
+struct partname_volume {
+       struct volume v;
+       char devname[16];
+       char parent_devname[16];
+};
+
+static struct driver partname_driver;
+
+static int partname_volume_identify(struct volume *v)
+{
+       int ret = FS_NONE;
+       FILE *f;
+
+       f = fopen(v->blk, "r");
+       if (!f)
+               return ret;
+
+       ret = block_file_identify(f, 0);
+
+       fclose(f);
+
+       return ret;
+}
+
+static int partname_volume_init(struct volume *v)
+{
+       struct partname_volume *p = container_of(v, struct partname_volume, v);
+       char voldir[BUFLEN];
+       char voldev[BUFLEN];
+       char pdev[BUFLEN];
+       unsigned int volsize;
+
+       snprintf(voldir, sizeof(voldir), "%s/%s", block_dir_name, p->devname);
+
+       if (read_uint_from_file(voldir, "size", &volsize))
+               return -1;
+
+       snprintf(voldev, sizeof(voldev), "/dev/%s", p->devname);
+       snprintf(pdev, sizeof(pdev), "/dev/%s", p->parent_devname);
+
+       v->type = BLOCKDEV;
+       v->size = volsize << 9; /* size is returned in sectors of 512 bytes */
+       v->blk = strdup(voldev);
+
+       return block_volume_format(v, 0, pdev);
+}
+
+/* from procd/utils.c -> should go to libubox */
+static char* get_cmdline_val(const char* name, char* out, int len)
+{
+       char line[1024], *c, *sptr;
+       int fd = open("/proc/cmdline", O_RDONLY);
+       ssize_t r = read(fd, line, sizeof(line) - 1);
+       close(fd);
+
+       if (r <= 0)
+               return NULL;
+
+       line[r] = 0;
+
+       for (c = strtok_r(line, " \t\n", &sptr); c;
+                       c = strtok_r(NULL, " \t\n", &sptr)) {
+               char *sep = strchr(c, '=');
+               if (sep == NULL)
+                       continue;
+
+               ssize_t klen = sep - c;
+               if (strncmp(name, c, klen) || name[klen] != 0)
+                       continue;
+
+               strncpy(out, &sep[1], len);
+               out[len-1] = 0;
+               return out;
+       }
+
+       return NULL;
+}
+
+static char *rootdevname(char *devpath) {
+       int l;
+
+       l = strlen(devpath) - 1;
+
+       /* strip partition suffix from root=/dev/... string */
+       while (l > 0 && (devpath[l] >= '0' && devpath[l] <= '9'))
+               --l;
+
+       if (devpath[l] != 'p')
+               ++l;
+
+       devpath[l] = '\0';
+
+       return basename(devpath);
+}
+
+static struct volume *partname_volume_find(char *name)
+{
+       struct partname_volume *p;
+       char volnamegstr[BUFLEN];
+       char namebuf[BUFLEN];
+       char rootparam[BUFLEN];
+       char *rootdev = NULL, *devname, *tmp;
+       int j;
+       bool found = false;
+       glob_t gl;
+
+       if (get_cmdline_val("root", rootparam, sizeof(rootparam))) {
+               rootdev = rootdevname(rootparam);
+               /* find partition on same device as rootfs */
+               snprintf(volnamegstr, sizeof(volnamegstr), "%s/%s/*/name", block_dir_name, rootdev);
+       } else {
+               /* no 'root=' kernel cmdline parameter, find on any block device */
+               snprintf(volnamegstr, sizeof(volnamegstr), "%s/*/name", block_dir_name);
+       }
+
+       if (!glob(volnamegstr, GLOB_NOESCAPE, NULL, &gl))
+               for (j = 0; j < gl.gl_pathc; j++) {
+                       if (!read_string_from_file("", gl.gl_pathv[j], namebuf, sizeof(namebuf)))
+                               continue;
+                       if (!strncmp(namebuf, name, sizeof(namebuf))) {
+                               found = 1;
+                               break;
+                       }
+               }
+
+       if (!found)
+               return NULL;
+
+       devname = gl.gl_pathv[j];
+       tmp = strrchr(devname, '/');
+       *tmp = '\0';
+       devname = strrchr(devname, '/') + 1;
+
+       p = calloc(1, sizeof(*p));
+       strncpy(p->devname, devname, sizeof(p->devname));
+       if (rootdev)
+               strncpy(p->parent_devname, rootdev, sizeof(p->devname));
+       else
+               strncpy(p->parent_devname, rootdevname(devname), sizeof(p->devname));
+
+       p->devname[sizeof(p->devname)-1] = '\0';
+       p->v.drv = &partname_driver;
+       p->v.name = strdup(namebuf);
+
+       return &p->v;
+}
+
+static struct driver partname_driver = {
+       .name = "partname",
+       .find = partname_volume_find,
+       .init = partname_volume_init,
+       .identify = partname_volume_identify,
+};
+
+DRIVER(partname_driver);