diff options
Diffstat (limited to 'extlinux/mountinfo.c')
| -rw-r--r-- | extlinux/mountinfo.c | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/extlinux/mountinfo.c b/extlinux/mountinfo.c new file mode 100644 index 00000000..2be87580 --- /dev/null +++ b/extlinux/mountinfo.c @@ -0,0 +1,277 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2012 Intel Corporation; All Rights Reserved + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, + * Boston MA 02110-1301, USA; either version 2 of the License, or + * (at your option) any later version; incorporated herein by reference. + * + * ----------------------------------------------------------------------- */ + +#include <stdio.h> +#include <string.h> +#include <limits.h> +#include <stdlib.h> +#include <errno.h> +#include <unistd.h> +#include <sys/stat.h> +#include <sys/sysmacros.h> +#include "mountinfo.h" + +/* + * Parse /proc/self/mountinfo + */ +static int get_string(FILE *f, char *string_buf, size_t string_len, char *ec) +{ + int ch; + char *p = string_buf; + + for (;;) { + if (!string_len) + return -2; /* String too long */ + + ch = getc(f); + if (ch == EOF) { + return -1; /* Got EOF */ + } else if (ch == ' ' || ch == '\t' || ch == '\n') { + *ec = ch; + *p = '\0'; + return p - string_buf; + } else if (ch == '\\') { + /* Should always be followed by 3 octal digits in 000..377 */ + int oc = 0; + int i; + for (i = 0; i < 3; i++) { + ch = getc(f); + if (ch < '0' || ch > '7' || (i == 0 && ch > '3')) + return -1; /* Bad escape sequence */ + oc = (oc << 3) + (ch - '0'); + } + if (!oc) + return -1; /* We can't handle \000 */ + *p++ = oc; + string_len--; + } else { + *p++ = ch; + string_len--; + } + } +} + +static void free_mountinfo(struct mountinfo *m) +{ + struct mountinfo *nx; + + while (m) { + free((char *)m->root); + free((char *)m->path); + free((char *)m->fstype); + free((char *)m->devpath); + free((char *)m->mountopt); + nx = m->next; + free(m); + m = nx; + } +} + +static struct mountinfo *head = NULL, **tail = &head; + +static void parse_mountinfo(void) +{ + FILE *f; + struct mountinfo *m, *mm; + char string_buf[PATH_MAX*8]; + int n; + char ec, *ep; + unsigned int ma, mi; + + f = fopen("/proc/self/mountinfo", "r"); + if (!f) + return; + + for (;;) { + m = malloc(sizeof(struct mountinfo)); + if (!m) + break; + memset(m, 0, sizeof *m); + + n = get_string(f, string_buf, sizeof string_buf, &ec); + if (n < 0 || ec == '\n') + break; + + m->mountid = strtoul(string_buf, &ep, 10); + if (*ep) + break; + + n = get_string(f, string_buf, sizeof string_buf, &ec); + if (n < 0 || ec == '\n') + break; + + m->parentid = strtoul(string_buf, &ep, 10); + if (*ep) + break; + + n = get_string(f, string_buf, sizeof string_buf, &ec); + if (n < 0 || ec == '\n') + break; + + if (sscanf(string_buf, "%u:%u", &ma, &mi) != 2) + break; + + m->dev = makedev(ma, mi); + + n = get_string(f, string_buf, sizeof string_buf, &ec); + if (n < 1 || ec == '\n' || string_buf[0] != '/') + break; + + m->root = strdup(string_buf); + if (!m->root) + break; + + n = get_string(f, string_buf, sizeof string_buf, &ec); + if (n < 1 || ec == '\n' || string_buf[0] != '/') + break; + + m->path = strdup(string_buf); + m->pathlen = (n == 1) ? 0 : n; /* Treat / as empty */ + + /* Skip tagged attributes */ + do { + n = get_string(f, string_buf, sizeof string_buf, &ec); + if (n < 0 || ec == '\n') + goto quit; + } while (n != 1 || string_buf[0] != '-'); + + n = get_string(f, string_buf, sizeof string_buf, &ec); + if (n < 0 || ec == '\n') + break; + + m->fstype = strdup(string_buf); + if (!m->fstype) + break; + + n = get_string(f, string_buf, sizeof string_buf, &ec); + if (n < 0 || ec == '\n') + break; + + m->devpath = strdup(string_buf); + if (!m->devpath) + break; + + n = get_string(f, string_buf, sizeof string_buf, &ec); + if (n < 0) + break; + + m->mountopt = strdup(string_buf); + if (!m->mountopt) + break; + + /* Skip any previously unknown fields */ + while (ec != '\n' && ec != EOF) + ec = getc(f); + + *tail = m; + tail = &m->next; + } +quit: + fclose(f); + free_mountinfo(m); + + /* Create parent links */ + for (m = head; m; m = m->next) { + for (mm = head; mm; mm = mm->next) { + if (m->parentid == mm->mountid) { + m->parent = mm; + if (!strcmp(m->path, mm->path)) + mm->hidden = 1; /* Hidden under another mount */ + break; + } + } + } +} + +const struct mountinfo *find_mount(const char *path, char **subpath) +{ + static int done_init; + char *real_path; + const struct mountinfo *m, *best; + struct stat st; + int len, matchlen; + + if (!done_init) { + parse_mountinfo(); + done_init = 1; + } + + if (stat(path, &st)) + return NULL; + + real_path = realpath(path, NULL); + if (!real_path) + return NULL; + + /* + * Tricky business: we need the longest matching subpath + * which isn't a parent of the same subpath. + */ + len = strlen(real_path); + matchlen = 0; + best = NULL; + for (m = head; m; m = m->next) { + if (m->hidden) + continue; /* Hidden underneath another mount */ + + if (m->pathlen > len) + continue; /* Cannot possibly match */ + + if (m->pathlen < matchlen) + continue; /* No point in testing this one */ + + if (st.st_dev == m->dev && + !memcmp(m->path, real_path, m->pathlen) && + (real_path[m->pathlen] == '/' || real_path[m->pathlen] == '\0')) { + matchlen = m->pathlen; + best = m; + } + } + + if (best && subpath) { + if (real_path[best->pathlen] == '\0') + *subpath = strdup("/"); + else + *subpath = strdup(real_path + best->pathlen); + } + + return best; +} + +#ifdef TEST + +int main(int argc, char *argv[]) +{ + int i; + const struct mountinfo *m; + char *subpath; + + parse_mountinfo(); + + for (i = 1; i < argc; i++) { + m = find_mount(argv[i], &subpath); + if (!m) { + printf("%s: %s\n", argv[i], strerror(errno)); + continue; + } + + printf("%s -> %s @ %s(%u,%u):%s %s %s\n", + argv[i], subpath, m->devpath, major(m->dev), minor(m->dev), + m->root, m->fstype, m->mountopt); + printf("Usable device: %s\n", find_device(m->dev, m->devpath)); + free(subpath); + } + + return 0; +} + +#endif |