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isosize: avoid reading more data than what is needed 

In same go fix error reporting when input file is not long enough.

$ touch empty
$ isosize empty
isosize: empty: might not be an ISO filesystem
isosize: read error on empty: Success

Signed-off-by: Sami Kerola <kerolasa@iki.fi>
This commit is contained in:
Sami Kerola 2017-05-27 21:18:57 +01:00 committed by Karel Zak
parent 504c03ecf8
commit e3e0054f5a
1 changed files with 10 additions and 47 deletions
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57
disk-utils/isosize.c
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@ -30,8 +30,6 @@
#include "strutils.h"
#include "closestream.h"
#define ISODCL(from, to) (to - from + 1)
static int is_iso(int fd)
{
char label[8];
@ -88,62 +86,27 @@ static int isonum_733(unsigned char *p, int xflag)
return (le);
}
struct iso_primary_descriptor
{
unsigned char type [ISODCL ( 1, 1)]; /* 711 */
unsigned char id [ISODCL ( 2, 6)];
unsigned char version [ISODCL ( 7, 7)]; /* 711 */
unsigned char unused1 [ISODCL ( 8, 8)];
unsigned char system_id [ISODCL ( 9, 40)]; /* auchars */
unsigned char volume_id [ISODCL ( 41, 72)]; /* duchars */
unsigned char unused2 [ISODCL ( 73, 80)];
unsigned char volume_space_size [ISODCL ( 81, 88)]; /* 733 */
unsigned char unused3 [ISODCL ( 89, 120)];
unsigned char volume_set_size [ISODCL ( 121, 124)]; /* 723 */
unsigned char volume_sequence_number [ISODCL ( 125, 128)]; /* 723 */
unsigned char logical_block_size [ISODCL ( 129, 132)]; /* 723 */
unsigned char path_table_size [ISODCL ( 133, 140)]; /* 733 */
unsigned char type_l_path_table [ISODCL ( 141, 144)]; /* 731 */
unsigned char opt_type_l_path_table [ISODCL ( 145, 148)]; /* 731 */
unsigned char type_m_path_table [ISODCL ( 149, 152)]; /* 732 */
unsigned char opt_type_m_path_table [ISODCL ( 153, 156)]; /* 732 */
unsigned char root_directory_record [ISODCL ( 157, 190)]; /* 9.1 */
unsigned char volume_set_id [ISODCL ( 191, 318)]; /* duchars */
unsigned char publisher_id [ISODCL ( 319, 446)]; /* achars */
unsigned char preparer_id [ISODCL ( 447, 574)]; /* achars */
unsigned char application_id [ISODCL ( 575, 702)]; /* achars */
unsigned char copyright_file_id [ISODCL ( 703, 739)]; /* 7.5 dchars */
unsigned char abstract_file_id [ISODCL ( 740, 776)]; /* 7.5 dchars */
unsigned char bibliographic_file_id [ISODCL ( 777, 813)]; /* 7.5 dchars */
unsigned char creation_date [ISODCL ( 814, 830)]; /* 8.4.26.1 */
unsigned char modification_date [ISODCL ( 831, 847)]; /* 8.4.26.1 */
unsigned char expiration_date [ISODCL ( 848, 864)]; /* 8.4.26.1 */
unsigned char effective_date [ISODCL ( 865, 881)]; /* 8.4.26.1 */
unsigned char file_structure_version [ISODCL ( 882, 882)]; /* 711 */
unsigned char unused4 [ISODCL ( 883, 883)];
unsigned char application_data [ISODCL ( 884, 1395)];
unsigned char unused5 [ISODCL (1396, 2048)];
};
static void isosize(int argc, char *filenamep, int xflag, long divisor)
{
int fd, nsecs, ssize;
struct iso_primary_descriptor ipd;
unsigned char volume_space_size[8];
unsigned char logical_block_size[4];
if ((fd = open(filenamep, O_RDONLY)) < 0)
err(EXIT_FAILURE, _("cannot open %s"), filenamep);
if (is_iso(fd))
warnx(_("%s: might not be an ISO filesystem"), filenamep);
if (lseek(fd, 16 << 11, 0) == (off_t) - 1)
err(EXIT_FAILURE, _("seek error on %s"), filenamep);
if (pread(fd, volume_space_size, sizeof(volume_space_size), 0x8050) <= 0 ||
pread(fd, logical_block_size, sizeof(logical_block_size), 0x8080) <= 0) {
if (errno)
err(EXIT_FAILURE, _("read error on %s"), filenamep);
errx(EXIT_FAILURE, _("read error on %s"), filenamep);
}
if (read(fd, &ipd, sizeof(ipd)) <= 0)
err(EXIT_FAILURE, _("read error on %s"), filenamep);
nsecs = isonum_733(ipd.volume_space_size, xflag);
nsecs = isonum_733(volume_space_size, xflag);
/* isonum_723 returns nowadays always 2048 */
ssize = isonum_723(ipd.logical_block_size, xflag);
ssize = isonum_723(logical_block_size, xflag);
if (1 < argc)
printf("%s: ", filenamep);