sbase

suckless unix tools
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commit ac694e6c4ac094f5f6f374f36ef6b72ea20bfaad
parent 74f680948e4cf1b4a5200c4b8774b7163d7bb7e1
Author: sin <sin@2f30.org>
Date:   Thu Apr 23 16:31:02 +0100

tar: Add routine to test if the tar archive is "legit"

Diffstat:
tar.c | 30++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+), 0 deletions(-)
diff --git a/tar.c b/tar.c @@ -353,6 +353,35 @@ sanitize(struct header *h) } static void +chktar(struct header *h) +{ + char tmp[8], *err; + char *p = (char *)h; + long s1, s2, i; + + if (h->prefix[0] == '\0' && h->name[0] == '\0') + goto bad; + if (strncmp("ustar", h->magic, 5)) + goto bad; + memcpy(tmp, h->chksum, sizeof(tmp)); + for (i = 0; i < sizeof(tmp); i++) + if (tmp[i] == ' ') + tmp[i] = '\0'; + s1 = strtol(tmp, &err, 8); + if (s1 < 0 || *err != '\0') + goto bad; + memset(h->chksum, ' ', sizeof(h->chksum)); + for (i = 0, s2 = 0; i < sizeof(*h); i++) + s2 += p[i]; + if (s1 != s2) + goto bad; + memcpy(h->chksum, tmp, sizeof(h->chksum)); + return; +bad: + eprintf("malformed tar archive\n"); +} + +static void xt(int argc, char *argv[], int (*fn)(char *, ssize_t, char[BLKSIZ])) { char b[BLKSIZ], fname[256 + 1], *p; @@ -363,6 +392,7 @@ xt(int argc, char *argv[], int (*fn)(char *, ssize_t, char[BLKSIZ])) int i, n; while (eread(tarfd, b, BLKSIZ) > 0 && h->name[0]) { + chktar(h); sanitize(h), n = 0; /* small dance around non-null terminated fields */