Look for full command names instead of substrings

like "un", "cat", and "lz" when determining if
xz is run as unxz, xzcat, lzma, unlzma, or lzcat.

This is to ensure that if xz is renamed (e.g. via
--program-transform-name), it doesn't so easily
work in wrong mode.

1 files changed, 13 insertions, 9 deletions

diff --git a/src/xz/args.c b/src/xz/args.c
index 97b22448..8d5d33c2 100644
--- a/src/xz/args.c
+++ b/src/xz/args.c
@@ -465,19 +465,23 @@ args_parse(args_info *args, int argc, char **argv)
 		// NOTE: It's possible that name[0] is now '\0' if argv[0]
 		// is weird, but it doesn't matter here.
 
-		// If the command name contains "lz",
-		// it implies --format=lzma.
-		if (strstr(name, "lz") != NULL)
+		// Look for full command names instead of substrings like
+		// "un", "cat", and "lz" to reduce possibility of false
+		// positives when the programs have been renamed.
+		if (strstr(name, "xzcat") != NULL) {
+			opt_mode = MODE_DECOMPRESS;
+			opt_stdout = true;
+		} else if (strstr(name, "unxz") != NULL) {
+			opt_mode = MODE_DECOMPRESS;
+		} else if (strstr(name, "lzcat") != NULL) {
 			opt_format = FORMAT_LZMA;
-
-		// Operation mode
-		if (strstr(name, "cat") != NULL) {
-			// Imply --decompress --stdout
 			opt_mode = MODE_DECOMPRESS;
 			opt_stdout = true;
-		} else if (strstr(name, "un") != NULL) {
-			// Imply --decompress
+		} else if (strstr(name, "unlzma") != NULL) {
+			opt_format = FORMAT_LZMA;
 			opt_mode = MODE_DECOMPRESS;
+		} else if (strstr(name, "lzma") != NULL) {
+			opt_format = FORMAT_LZMA;
 		}
 	}