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authorDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2019-06-27 14:21:54 +0200
committerDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2019-06-27 16:54:21 +0200
commit154532d71c447e73c70ec06d26628bb6919b9a5a (patch)
treea9f0bbd95d1f1e4bec4406f2c8e742bd320ac04a
parente87a6a28cffac4044f365b90af9f11a8acb5f83c (diff)
Relax tar header parser to accept pre-posix formats
Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
-rw-r--r--include/tar.h10
-rw-r--r--lib/tar/read_header.c42
-rw-r--r--tests/tar_formats.c34
3 files changed, 76 insertions, 10 deletions
diff --git a/include/tar.h b/include/tar.h
index a39d7c9..3b7c8eb 100644
--- a/include/tar.h
+++ b/include/tar.h
@@ -6,6 +6,13 @@
#include <stdbool.h>
#include <stdint.h>
+typedef enum {
+ ETV_UNKNOWN = 0,
+ ETV_V7_UNIX,
+ ETV_PRE_POSIX,
+ ETV_POSIX,
+} E_TAR_VERSION;
+
typedef struct {
char name[100];
char mode[8];
@@ -46,6 +53,9 @@ typedef struct {
#define TAR_MAGIC "ustar"
#define TAR_VERSION "00"
+#define TAR_MAGIC_OLD "ustar "
+#define TAR_VERSION_OLD " "
+
/*
Returns < 0 on failure, > 0 if cannot encode, 0 on success.
Prints error/warning messages to stderr.
diff --git a/lib/tar/read_header.c b/lib/tar/read_header.c
index ec48a3e..01e4543 100644
--- a/lib/tar/read_header.c
+++ b/lib/tar/read_header.c
@@ -25,6 +25,11 @@ static int read_octal(const char *str, int digits, uint64_t *out)
{
uint64_t result = 0;
+ while (digits > 0 && isspace(*str)) {
+ ++str;
+ --digits;
+ }
+
while (digits > 0 && *str >= '0' && *str <= '7') {
if (result > 0x1FFFFFFFFFFFFFFFUL) {
fputs("numeric overflow parsing tar header\n", stderr);
@@ -43,6 +48,11 @@ static int read_binary(const char *str, int digits, uint64_t *out)
{
uint64_t x, result = 0;
+ while (digits > 0 && isspace(*str)) {
+ ++str;
+ --digits;
+ }
+
while (digits > 0) {
if (result > 0x00FFFFFFFFFFFFFFUL) {
fputs("numeric overflow parsing tar header\n", stderr);
@@ -96,15 +106,24 @@ static bool is_checksum_valid(const tar_header_t *hdr)
return chksum == ref;
}
-static bool is_magic_valid(const tar_header_t *hdr)
+static E_TAR_VERSION check_version(const tar_header_t *hdr)
{
- if (memcmp(hdr->magic, TAR_MAGIC, sizeof(hdr->magic)) != 0)
- return false;
+ char buffer[sizeof(hdr->magic) + sizeof(hdr->version)];
- if (memcmp(hdr->version, TAR_VERSION, sizeof(hdr->version)) != 0)
- return false;
+ memset(buffer, '\0', sizeof(buffer));
+ if (memcmp(hdr->magic, buffer, sizeof(hdr->magic)) == 0 &&
+ memcmp(hdr->version, buffer, sizeof(hdr->version)) == 0)
+ return ETV_V7_UNIX;
+
+ if (memcmp(hdr->magic, TAR_MAGIC, sizeof(hdr->magic)) == 0 &&
+ memcmp(hdr->version, TAR_VERSION, sizeof(hdr->version)) == 0)
+ return ETV_POSIX;
+
+ if (memcmp(hdr->magic, TAR_MAGIC_OLD, sizeof(hdr->magic)) == 0 &&
+ memcmp(hdr->version, TAR_VERSION_OLD, sizeof(hdr->version)) == 0)
+ return ETV_PRE_POSIX;
- return true;
+ return ETV_UNKNOWN;
}
static int pax_read_decimal(const char *str, uint64_t *out)
@@ -232,13 +251,14 @@ fail:
}
static int decode_header(const tar_header_t *hdr, unsigned int set_by_pax,
- tar_header_decoded_t *out)
+ tar_header_decoded_t *out, E_TAR_VERSION version)
{
uint64_t field;
size_t count;
if (!(set_by_pax & PAX_NAME)) {
- if (hdr->prefix[0] != '\0') {
+ if (hdr->tail.posix.prefix[0] != '\0' &&
+ version == ETV_POSIX) {
count = strlen(hdr->name) + 1;
count += strlen(hdr->prefix) + 1;
@@ -356,6 +376,7 @@ int read_header(int fd, tar_header_decoded_t *out)
{
unsigned int set_by_pax = 0;
bool prev_was_zero = false;
+ E_TAR_VERSION version;
uint64_t pax_size;
tar_header_t hdr;
int ret;
@@ -379,8 +400,9 @@ int read_header(int fd, tar_header_decoded_t *out)
}
prev_was_zero = false;
+ version = check_version(&hdr);
- if (!is_magic_valid(&hdr))
+ if (version == ETV_UNKNOWN)
goto fail_magic;
if (!is_checksum_valid(&hdr))
@@ -398,7 +420,7 @@ int read_header(int fd, tar_header_decoded_t *out)
break;
}
- if (decode_header(&hdr, set_by_pax, out))
+ if (decode_header(&hdr, set_by_pax, out, version))
goto fail;
return 0;
diff --git a/tests/tar_formats.c b/tests/tar_formats.c
index e09730b..58cd223 100644
--- a/tests/tar_formats.c
+++ b/tests/tar_formats.c
@@ -68,5 +68,39 @@ int main(void)
clear_header(&hdr);
close(fd);
+ fd = open_read("format-acceptance/ustar-pre-posix.tar");
+ assert(read_header(fd, &hdr) == 0);
+ assert(hdr.sb.st_mode == (S_IFREG | 0644));
+ assert(hdr.sb.st_uid == 01750);
+ assert(hdr.sb.st_gid == 01750);
+ assert(hdr.sb.st_size == 5);
+ assert(hdr.sb.st_mtime == 1542905892);
+ assert(hdr.sb.st_atime == 1542905892);
+ assert(hdr.sb.st_ctime == 1542905892);
+ assert(strcmp(hdr.name, "input.txt") == 0);
+ assert(!hdr.unknown_record);
+ assert(read_retry(fd, buffer, 5) == 5);
+ buffer[5] = '\0';
+ assert(strcmp(buffer, "test\n") == 0);
+ clear_header(&hdr);
+ close(fd);
+
+ fd = open_read("format-acceptance/v7.tar");
+ assert(read_header(fd, &hdr) == 0);
+ assert(hdr.sb.st_mode == (S_IFREG | 0644));
+ assert(hdr.sb.st_uid == 01750);
+ assert(hdr.sb.st_gid == 01750);
+ assert(hdr.sb.st_size == 5);
+ assert(hdr.sb.st_mtime == 1542905892);
+ assert(hdr.sb.st_atime == 1542905892);
+ assert(hdr.sb.st_ctime == 1542905892);
+ assert(strcmp(hdr.name, "input.txt") == 0);
+ assert(!hdr.unknown_record);
+ assert(read_retry(fd, buffer, 5) == 5);
+ buffer[5] = '\0';
+ assert(strcmp(buffer, "test\n") == 0);
+ clear_header(&hdr);
+ close(fd);
+
return EXIT_SUCCESS;
}