/* vi: set sw=4 ts=4: */ /* * read.c - read the blkid cache from disk, to avoid scanning all devices * * Copyright (C) 2001, 2003 Theodore Y. Ts'o * Copyright (C) 2001 Andreas Dilger * * %Begin-Header% * This file may be redistributed under the terms of the * GNU Lesser General Public License. * %End-Header% */ #include <stdio.h> #include <ctype.h> #include <string.h> #include <time.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> #include <errno.h> #include "blkidP.h" #include "../uuid/uuid.h" #ifdef HAVE_STRTOULL #define __USE_ISOC9X #define STRTOULL strtoull /* defined in stdlib.h if you try hard enough */ #else /* FIXME: need to support real strtoull here */ #define STRTOULL strtoul #endif #include <stdlib.h> #ifdef TEST_PROGRAM #define blkid_debug_dump_dev(dev) (debug_dump_dev(dev)) static void debug_dump_dev(blkid_dev dev); #endif /* * File format: * * <device [<NAME="value"> ...]>device_name</device> * * The following tags are required for each entry: * <ID="id"> unique (within this file) ID number of this device * <TIME="time"> (ascii time_t) time this entry was last read from disk * <TYPE="type"> (detected) type of filesystem/data for this partition * * The following tags may be present, depending on the device contents * <LABEL="label"> (user supplied) label (volume name, etc) * <UUID="uuid"> (generated) universally unique identifier (serial no) */ static char *skip_over_blank(char *cp) { while (*cp && isspace(*cp)) cp++; return cp; } static char *skip_over_word(char *cp) { char ch; while ((ch = *cp)) { /* If we see a backslash, skip the next character */ if (ch == '\\') { cp++; if (*cp == '\0') break; cp++; continue; } if (isspace(ch) || ch == '<' || ch == '>') break; cp++; } return cp; } static char *strip_line(char *line) { char *p; line = skip_over_blank(line); p = line + strlen(line) - 1; while (*line) { if (isspace(*p)) *p-- = '\0'; else break; } return line; } /* * Start parsing a new line from the cache. * * line starts with "<device" return 1 -> continue parsing line * line starts with "<foo", empty, or # return 0 -> skip line * line starts with other, return -BLKID_ERR_CACHE -> error */ static int parse_start(char **cp) { char *p; p = strip_line(*cp); /* Skip comment or blank lines. We can't just NUL the first '#' char, * in case it is inside quotes, or escaped. */ if (*p == '\0' || *p == '#') return 0; if (!strncmp(p, "<device", 7)) { DBG(DEBUG_READ, printf("found device header: %8s\n", p)); p += 7; *cp = p; return 1; } if (*p == '<') return 0; return -BLKID_ERR_CACHE; } /* Consume the remaining XML on the line (cosmetic only) */ static int parse_end(char **cp) { *cp = skip_over_blank(*cp); if (!strncmp(*cp, "</device>", 9)) { DBG(DEBUG_READ, printf("found device trailer %9s\n", *cp)); *cp += 9; return 0; } return -BLKID_ERR_CACHE; } /* * Allocate a new device struct with device name filled in. Will handle * finding the device on lines of the form: * <device foo=bar>devname</device> * <device>devname<foo>bar</foo></device> */ static int parse_dev(blkid_cache cache, blkid_dev *dev, char **cp) { char *start, *tmp, *end, *name; int ret; if ((ret = parse_start(cp)) <= 0) return ret; start = tmp = strchr(*cp, '>'); if (!start) { DBG(DEBUG_READ, printf("blkid: short line parsing dev: %s\n", *cp)); return -BLKID_ERR_CACHE; } start = skip_over_blank(start + 1); end = skip_over_word(start); DBG(DEBUG_READ, printf("device should be %*s\n", end - start, start)); if (**cp == '>') *cp = end; else (*cp)++; *tmp = '\0'; if (!(tmp = strrchr(end, '<')) || parse_end(&tmp) < 0) { DBG(DEBUG_READ, printf("blkid: missing </device> ending: %s\n", end)); } else if (tmp) *tmp = '\0'; if (end - start <= 1) { DBG(DEBUG_READ, printf("blkid: empty device name: %s\n", *cp)); return -BLKID_ERR_CACHE; } name = blkid_strndup(start, end-start); if (name == NULL) return -BLKID_ERR_MEM; DBG(DEBUG_READ, printf("found dev %s\n", name)); if (!(*dev = blkid_get_dev(cache, name, BLKID_DEV_CREATE))) return -BLKID_ERR_MEM; free(name); return 1; } /* * Extract a tag of the form NAME="value" from the line. */ static int parse_token(char **name, char **value, char **cp) { char *end; if (!name || !value || !cp) return -BLKID_ERR_PARAM; if (!(*value = strchr(*cp, '='))) return 0; **value = '\0'; *name = strip_line(*cp); *value = skip_over_blank(*value + 1); if (**value == '"') { end = strchr(*value + 1, '"'); if (!end) { DBG(DEBUG_READ, printf("unbalanced quotes at: %s\n", *value)); *cp = *value; return -BLKID_ERR_CACHE; } (*value)++; *end = '\0'; end++; } else { end = skip_over_word(*value); if (*end) { *end = '\0'; end++; } } *cp = end; return 1; } /* * Extract a tag of the form <NAME>value</NAME> from the line. */ /* static int parse_xml(char **name, char **value, char **cp) { char *end; if (!name || !value || !cp) return -BLKID_ERR_PARAM; *name = strip_line(*cp); if ((*name)[0] != '<' || (*name)[1] == '/') return 0; FIXME: finish this. } */ /* * Extract a tag from the line. * * Return 1 if a valid tag was found. * Return 0 if no tag found. * Return -ve error code. */ static int parse_tag(blkid_cache cache, blkid_dev dev, char **cp) { char *name; char *value; int ret; if (!cache || !dev) return -BLKID_ERR_PARAM; if ((ret = parse_token(&name, &value, cp)) <= 0 /* && (ret = parse_xml(&name, &value, cp)) <= 0 */) return ret; /* Some tags are stored directly in the device struct */ if (!strcmp(name, "DEVNO")) dev->bid_devno = STRTOULL(value, 0, 0); else if (!strcmp(name, "PRI")) dev->bid_pri = strtol(value, 0, 0); else if (!strcmp(name, "TIME")) /* FIXME: need to parse a long long eventually */ dev->bid_time = strtol(value, 0, 0); else ret = blkid_set_tag(dev, name, value, strlen(value)); DBG(DEBUG_READ, printf(" tag: %s=\"%s\"\n", name, value)); return ret < 0 ? ret : 1; } /* * Parse a single line of data, and return a newly allocated dev struct. * Add the new device to the cache struct, if one was read. * * Lines are of the form <device [TAG="value" ...]>/dev/foo</device> * * Returns -ve value on error. * Returns 0 otherwise. * If a valid device was read, *dev_p is non-NULL, otherwise it is NULL * (e.g. comment lines, unknown XML content, etc). */ static int blkid_parse_line(blkid_cache cache, blkid_dev *dev_p, char *cp) { blkid_dev dev; int ret; if (!cache || !dev_p) return -BLKID_ERR_PARAM; *dev_p = NULL; DBG(DEBUG_READ, printf("line: %s\n", cp)); if ((ret = parse_dev(cache, dev_p, &cp)) <= 0) return ret; dev = *dev_p; while ((ret = parse_tag(cache, dev, &cp)) > 0) { ; } if (dev->bid_type == NULL) { DBG(DEBUG_READ, printf("blkid: device %s has no TYPE\n",dev->bid_name)); blkid_free_dev(dev); } DBG(DEBUG_READ, blkid_debug_dump_dev(dev)); return ret; } /* * Parse the specified filename, and return the data in the supplied or * a newly allocated cache struct. If the file doesn't exist, return a * new empty cache struct. */ void blkid_read_cache(blkid_cache cache) { FILE *file; char buf[4096]; int fd, lineno = 0; struct stat st; if (!cache) return; /* * If the file doesn't exist, then we just return an empty * struct so that the cache can be populated. */ if ((fd = open(cache->bic_filename, O_RDONLY)) < 0) return; if (fstat(fd, &st) < 0) goto errout; if ((st.st_mtime == cache->bic_ftime) || (cache->bic_flags & BLKID_BIC_FL_CHANGED)) { DBG(DEBUG_CACHE, printf("skipping re-read of %s\n", cache->bic_filename)); goto errout; } DBG(DEBUG_CACHE, printf("reading cache file %s\n", cache->bic_filename)); file = xfdopen_for_read(fd); while (fgets(buf, sizeof(buf), file)) { blkid_dev dev; unsigned int end; lineno++; if (buf[0] == 0) continue; end = strlen(buf) - 1; /* Continue reading next line if it ends with a backslash */ while (buf[end] == '\\' && end < sizeof(buf) - 2 && fgets(buf + end, sizeof(buf) - end, file)) { end = strlen(buf) - 1; lineno++; } if (blkid_parse_line(cache, &dev, buf) < 0) { DBG(DEBUG_READ, printf("blkid: bad format on line %d\n", lineno)); continue; } } fclose(file); /* * Initially we do not need to write out the cache file. */ cache->bic_flags &= ~BLKID_BIC_FL_CHANGED; cache->bic_ftime = st.st_mtime; return; errout: close(fd); } #ifdef TEST_PROGRAM static void debug_dump_dev(blkid_dev dev) { struct list_head *p; if (!dev) { printf(" dev: NULL\n"); return; } printf(" dev: name = %s\n", dev->bid_name); printf(" dev: DEVNO=\"0x%0llx\"\n", dev->bid_devno); printf(" dev: TIME=\"%lu\"\n", dev->bid_time); printf(" dev: PRI=\"%d\"\n", dev->bid_pri); printf(" dev: flags = 0x%08X\n", dev->bid_flags); list_for_each(p, &dev->bid_tags) { blkid_tag tag = list_entry(p, struct blkid_struct_tag, bit_tags); if (tag) printf(" tag: %s=\"%s\"\n", tag->bit_name, tag->bit_val); else printf(" tag: NULL\n"); } bb_putchar('\n'); } int main(int argc, char**argv) { blkid_cache cache = NULL; int ret; blkid_debug_mask = DEBUG_ALL; if (argc > 2) { fprintf(stderr, "Usage: %s [filename]\n" "Test parsing of the cache (filename)\n", argv[0]); exit(1); } if ((ret = blkid_get_cache(&cache, argv[1])) < 0) fprintf(stderr, "error %d reading cache file %s\n", ret, argv[1] ? argv[1] : BLKID_CACHE_FILE); blkid_put_cache(cache); return ret; } #endif