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base32/64: decode in-place

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2020-11-27 15:39:23 +01:00
parent c8b3d9a145
commit cdab3c4fac
1 changed files with 12 additions and 5 deletions
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17
coreutils/uudecode.c
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@ -286,13 +286,19 @@ int baseNUM_main(int argc UNUSED_PARAM, char **argv)
} else { } else {
enum { enum {
SRC_BUF_SIZE = 3 * 5 * 32, /* this *MUST* be a multiple of 3 and 5 */ SRC_BUF_SIZE = 3 * 5 * 32, /* this *MUST* be a multiple of 3 and 5 */
DST_BUF_SIZE = 4 * ((SRC_BUF_SIZE + 2) / 3), DST_BUF_SIZE = 8 * ((SRC_BUF_SIZE + 4) / 5), /* max growth on decode (base32 case) */
}; };
char src_buf[SRC_BUF_SIZE]; /* Use one buffer for both input and output:
char dst_buf[DST_BUF_SIZE + 1]; * decoding reads input "left-to-right",
int src_fd = fileno(src_stream); * it's safe to place source at the end of the buffer and
int rem = 0; * overwrite it while decoding, just be careful to have a gap.
*/
char dst_buf[((DST_BUF_SIZE + /*gap:*/ 16) /*round up to 16:*/ | 0xf) + 1];
#define src_buf (dst_buf + sizeof(dst_buf) - SRC_BUF_SIZE)
int src_fd, rem;
src_fd = fileno(src_stream);
rem = 0;
while (1) { while (1) {
size_t size = full_read(src_fd, src_buf, SRC_BUF_SIZE); size_t size = full_read(src_fd, src_buf, SRC_BUF_SIZE);
if ((ssize_t)size < 0) if ((ssize_t)size < 0)
@ -331,6 +337,7 @@ int baseNUM_main(int argc UNUSED_PARAM, char **argv)
} }
} }
} }
#undef src_buf
} }
fflush_stdout_and_exit(EXIT_SUCCESS); fflush_stdout_and_exit(EXIT_SUCCESS);