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Improve error detection and check gzip header CRC if present.
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@madler
madler committed Jan 22, 2015
1 parent fbe3e26 commit 1100df6
Showing 1 changed file with 57 additions and 40 deletions.
97 changes: 57 additions & 40 deletions pigz.c
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Expand Up @@ -2362,12 +2362,31 @@ local void in_init(void)
while (togo > g.in_left) { \
togo -= g.in_left; \
if (load() == 0) \
return -1; \
return -3; \
} \
g.in_left -= togo; \
g.in_next += togo; \
} while (0)

/* GET(), GET2(), GET4() and SKIP() equivalents, with crc update */
#define GETC() (g.in_left == 0 && (g.in_eof || load() == 0) ? 0 : \
(g.in_left--, crc = crc32(crc, g.in_next, 1), *g.in_next++))
#define GET2C() (tmp2 = GETC(), tmp2 + ((unsigned)(GETC()) << 8))
#define GET4C() (tmp4 = GET2C(), tmp4 + ((unsigned long)(GET2C()) << 16))
#define SKIPC(dist) \
do { \
size_t togo = (dist); \
while (togo > g.in_left) { \
crc = crc32(crc, g.in_next, g.in_left); \
togo -= g.in_left; \
if (load() == 0) \
return -3; \
} \
crc = crc32(crc, g.in_next, togo); \
g.in_left -= togo; \
g.in_next += togo; \
} while (0)

/* pull LSB order or MSB order integers from an unsigned char buffer */
#define PULL2L(p) ((p)[0] + ((unsigned)((p)[1]) << 8))
#define PULL4L(p) (PULL2L(p) + ((unsigned long)(PULL2L((p) + 2)) << 16))
Expand Down Expand Up @@ -2455,9 +2474,10 @@ local int read_extra(unsigned len, int save)
range 0..256 (256 implies a zip method greater than 255), or on error return
negative: -1 is immediate EOF, -2 is not a recognized compressed format, -3
is premature EOF within the header, -4 is unexpected header flag values, -5
is the zip central directory; a method of 257 is lzw -- if the return value
is not negative, then get_header() sets g.form to indicate gzip (0), zlib
(1), or zip (2, or 3 if the entry is followed by a data descriptor) */
is the zip central directory, -6 is a failed gzip header crc check; a method
of 257 is lzw -- if the return value is not negative, then get_header() sets
g.form to indicate gzip (0), zlib (1), or zip (2, or 3 if the entry is
followed by a data descriptor) */
local int get_header(int save)
{
unsigned magic; /* magic header */
Expand All @@ -2466,6 +2486,7 @@ local int get_header(int save)
unsigned fname, extra; /* name and extra field lengths */
unsigned tmp2; /* for macro */
unsigned long tmp4; /* for macro */
unsigned long crc; /* gzip header crc */

/* clear return information */
if (save) {
Expand All @@ -2482,9 +2503,10 @@ local int get_header(int save)
magic += GET();
if (g.in_eof)
return -2;
if (magic % 31 == 0) { /* it's zlib */
if (magic % 31 == 0 && (magic & 0x8f20) == 0x0800) {
/* it's zlib */
g.form = 1;
return (int)((magic >> 8) & 0xf);
return 8;
}
if (magic == 0x1f9d) /* it's lzw */
return 257;
Expand All @@ -2498,15 +2520,11 @@ local int get_header(int save)
return -4; /* not a local header */
SKIP(2);
flags = GET2();
if (g.in_eof)
return -3;
if (flags & 0xfff0)
return -4;
method = GET(); /* return low byte of method or 256 */
if (GET() != 0 || flags & 1)
method = 256; /* unknown or encrypted */
if (g.in_eof)
return -3;
if (save)
g.stamp = dos2time(GET4());
else
Expand All @@ -2517,7 +2535,11 @@ local int get_header(int save)
fname = GET2();
extra = GET2();
if (save) {
char *next = g.hname = alloc(NULL, fname + 1);
char *next;

if (g.in_eof)
return -3;
next = g.hname = alloc(NULL, fname + 1);
while (fname > g.in_left) {
memcpy(next, g.in_next, g.in_left);
fname -= g.in_left;
Expand All @@ -2544,35 +2566,29 @@ local int get_header(int save)
}

/* it's gzip -- get method and flags */
method = GET();
flags = GET();
if (g.in_eof)
return -1;
crc = 0xf6e946c9; /* crc of 0x1f 0x8b */
method = GETC();
flags = GETC();
if (flags & 0xe0)
return -4;

/* get time stamp */
if (save)
g.stamp = tolong(GET4());
g.stamp = tolong(GET4C());
else
SKIP(4);
SKIPC(4);

/* skip extra field and OS */
SKIP(2);
SKIPC(2);

/* skip extra field, if present */
if (flags & 4) {
extra = GET2();
if (g.in_eof)
return -3;
SKIP(extra);
}
if (flags & 4)
SKIPC(GET2C());

/* read file name, if present, into allocated memory */
if ((flags & 8) && save) {
unsigned char *end;
size_t copy, have, size = 0;
g.hname = NULL;
have = 0;
do {
if (g.in_left == 0 && load() == 0)
Expand All @@ -2583,25 +2599,24 @@ local int get_header(int save)
g.in_left -= copy;
g.in_next += copy;
} while (end == NULL);
crc = crc32(crc, (unsigned char *)g.hname, have);
}
else if (flags & 8)
while (GET() != 0)
if (g.in_eof)
return -3;
while (GETC() != 0)
;

/* skip comment */
if (flags & 16)
while (GET() != 0)
if (g.in_eof)
return -3;
while (GETC() != 0)
;

/* skip header crc */
if (flags & 2)
SKIP(2);
/* check header crc */
if ((flags & 2) && GET2() != (crc & 0xffff))
return -6;

/* return gzip compression method */
g.form = 0;
return method;
return g.in_eof ? -3 : method;
}

/* --- list contents of compressed input (gzip, zlib, or lzw) */
Expand Down Expand Up @@ -2742,7 +2757,8 @@ local void list_info(void)
if (method < 0) {
RELEASE(g.hname);
if (method != -1 && g.verbosity > 1)
complain("skipping: %s not a compressed file", g.inf);
complain(method != -6 ? "skipping: %s not compressed" :
"skipping: %s corrupted: invalid header crc", g.inf);
return;
}

Expand Down Expand Up @@ -3514,7 +3530,7 @@ local void process(char *path)
SET_BINARY_MODE(g.ind);

/* if decoding or testing, try to read gzip header */
g.hname = NULL;
RELEASE(g.hname);
if (g.decode) {
in_init();
method = get_header(1);
Expand All @@ -3526,9 +3542,10 @@ local void process(char *path)
if (g.ind != 0)
close(g.ind);
if (method != -1)
complain(method < 0 ? "skipping: %s is not compressed" :
"skipping: %s has unknown compression method",
g.inf);
complain(method < 0 ?
method != -6 ? "skipping: %s is not compressed" :
"skipping: %s corrupted: invalid header crc" :
"skipping: %s has unknown compression method", g.inf);
return;
}

Expand Down

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