diff options
author | Christos Zoulas <christos@zoulas.com> | 2017-03-17 20:45:01 +0000 |
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committer | Christos Zoulas <christos@zoulas.com> | 2017-03-17 20:45:01 +0000 |
commit | 306769180f13f5907ea579cfaac76aef39d40eb4 (patch) | |
tree | 7073cc0dc39cf1d3b9fa89c1e2c0e2f86ef7ca29 | |
parent | 5dd25314a817a747c2190226b889f648515f8d29 (diff) | |
download | file-git-306769180f13f5907ea579cfaac76aef39d40eb4.tar.gz |
Although I can't reproduce it, oss-fuzz complains about is_tar. So rewrite
it to make it more obvious what's going on.
-rw-r--r-- | src/is_tar.c | 37 |
1 files changed, 22 insertions, 15 deletions
diff --git a/src/is_tar.c b/src/is_tar.c index a3e5dbf2..1953a7fc 100644 --- a/src/is_tar.c +++ b/src/is_tar.c @@ -40,7 +40,7 @@ #include "file.h" #ifndef lint -FILE_RCSID("@(#)$File: is_tar.c,v 1.38 2015/04/09 20:01:41 christos Exp $") +FILE_RCSID("@(#)$File: is_tar.c,v 1.39 2017/03/17 20:45:01 christos Exp $") #endif #include "magic.h" @@ -51,7 +51,7 @@ FILE_RCSID("@(#)$File: is_tar.c,v 1.38 2015/04/09 20:01:41 christos Exp $") #define isodigit(c) ( ((c) >= '0') && ((c) <= '7') ) private int is_tar(const unsigned char *, size_t); -private int from_oct(int, const char *); /* Decode octal number */ +private int from_oct(const char *, size_t); /* Decode octal number */ static const char tartype[][32] = { "tar archive", @@ -93,31 +93,35 @@ private int is_tar(const unsigned char *buf, size_t nbytes) { const union record *header = (const union record *)(const void *)buf; - int i; - int sum, recsum; - const unsigned char *p; + size_t i; + int sum, recsum; + const unsigned char *p, *ep; - if (nbytes < sizeof(union record)) + if (nbytes < sizeof(*header)) return 0; - recsum = from_oct(8, header->header.chksum); + recsum = from_oct(header->header.chksum, sizeof(header->header.chksum)); sum = 0; p = header->charptr; - for (i = sizeof(union record); --i >= 0;) + ep = header->charptr + sizeof(*header); + while (p < ep) sum += *p++; /* Adjust checksum to count the "chksum" field as blanks. */ - for (i = sizeof(header->header.chksum); --i >= 0;) + for (i = 0; i < sizeof(header->header.chksum); i++) sum -= header->header.chksum[i]; - sum += ' ' * sizeof header->header.chksum; + sum += ' ' * sizeof(header->header.chksum); if (sum != recsum) return 0; /* Not a tar archive */ - if (strcmp(header->header.magic, GNUTMAGIC) == 0) + if (strncmp(header->header.magic, GNUTMAGIC, + sizeof(header->header.magic)) == 0) return 3; /* GNU Unix Standard tar archive */ - if (strcmp(header->header.magic, TMAGIC) == 0) + + if (strncmp(header->header.magic, TMAGIC, + sizeof(header->header.magic)) == 0) return 2; /* Unix Standard tar archive */ return 1; /* Old fashioned tar archive */ @@ -130,19 +134,22 @@ is_tar(const unsigned char *buf, size_t nbytes) * Result is -1 if the field is invalid (all blank, or non-octal). */ private int -from_oct(int digs, const char *where) +from_oct(const char *where, size_t digs) { int value; + if (digs == 0) + return -1; + while (isspace((unsigned char)*where)) { /* Skip spaces */ where++; - if (--digs <= 0) + if (digs-- == 0) return -1; /* All blank field */ } value = 0; while (digs > 0 && isodigit(*where)) { /* Scan til non-octal */ value = (value << 3) | (*where++ - '0'); - --digs; + digs--; } if (digs > 0 && *where && !isspace((unsigned char)*where)) |