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authorDenys Vlasenko <vda.linux@googlemail.com>2020-11-27 15:39:23 +0100
committerDenys Vlasenko <vda.linux@googlemail.com>2020-11-27 15:39:23 +0100
commitcdab3c4fac76bcf941e55e309b061ac97925f9b0 (patch)
treeaa7c3895c8cfc09140c6e7f3d79ca9e8a3a21059
parentc8b3d9a145d2db95869f0ae8081d85c0378f0aef (diff)
downloadbusybox-cdab3c4fac76bcf941e55e309b061ac97925f9b0.tar.gz
base32/64: decode in-place
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--coreutils/uudecode.c17
1 files changed, 12 insertions, 5 deletions
diff --git a/coreutils/uudecode.c b/coreutils/uudecode.c
index 751976a87..10e5a55de 100644
--- a/coreutils/uudecode.c
+++ b/coreutils/uudecode.c
@@ -286,13 +286,19 @@ int baseNUM_main(int argc UNUSED_PARAM, char **argv)
} else {
enum {
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];
- char dst_buf[DST_BUF_SIZE + 1];
- int src_fd = fileno(src_stream);
- int rem = 0;
+ /* Use one buffer for both input and output:
+ * decoding reads input "left-to-right",
+ * it's safe to place source at the end of the buffer and
+ * 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) {
size_t size = full_read(src_fd, src_buf, SRC_BUF_SIZE);
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);