From 24e765a099ed615378423a411b36ab156bd08f9a Mon Sep 17 00:00:00 2001
From: Nexory <St4yl3r30@hotmail.de>
Date: Thu, 22 Oct 2026 00:06:47 +0200
Subject: [PATCH 1/2] cli: --rm skips -t and stdin

The manual says that -t neither creates nor removes files, and that
--rm deletes the source after a successful compression or
decompression. The CLI did not follow it for two cases :

- `lz4 -t --rm file.lz4` tested the file, then deleted it.
- With stdin as source, the output was complete, but remove("stdin")
  failed and the command ended with "Remove error : stdin"
  (exit code 50 when compressing, 45 when decompressing).
  A file named `stdin` in the working directory would have been deleted.

One helper, LZ4IO_mustRemoveSrcFile(), now decides. It answers no in
test mode and for stdin, and both remove sites use it :
LZ4IO_finishCompressedFile() and LZ4IO_decompressSrcFile().
A regular source file is still removed.
---
 programs/lz4io.c        | 15 +++++++++++++--
 tests/test-lz4-basic.sh | 11 +++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/programs/lz4io.c b/programs/lz4io.c
index 5d7a162b..36392500 100644
--- a/programs/lz4io.c
+++ b/programs/lz4io.c
@@ -423,6 +423,17 @@ static int LZ4IO_isStdout(const char* s)
     return UTIL_sameString(s, stdoutmark);
 }
 
+/* LZ4IO_mustRemoveSrcFile() :
+ * `--rm` only applies to a regular source file :
+ * not in test mode, which removes nothing (see lz4.1.md),
+ * and not when reading from stdin, which is not a file. */
+static int LZ4IO_mustRemoveSrcFile(const LZ4IO_prefs_t* prefs, const char* srcFileName)
+{
+    return prefs->removeSrcFile
+        && !prefs->testMode
+        && !LZ4IO_isStdin(srcFileName);
+}
+
 
 /* ************************************************************************ **
 ** ********************** LZ4 File / Pipe compression ********************* **
@@ -881,7 +892,7 @@ LZ4IO_finishCompressedFile(FILE* srcFile, FILE* dstFile,
             UTIL_setFileStat(dstFileName, &statbuf);
     }   }
 
-    if (io_prefs->removeSrcFile && !srcModified && !srcReplaced) {  /* remove source file : --rm */
+    if (LZ4IO_mustRemoveSrcFile(io_prefs, srcFileName) && !srcModified && !srcReplaced) {  /* remove source file : --rm */
         if (remove(srcFileName))
             END_PROCESS(50, "Remove error : %s: %s", srcFileName, strerror(errno));
     }
@@ -2637,7 +2648,7 @@ LZ4IO_decompressSrcFile(unsigned long long* outGenSize,
 
     /* Close input */
     fclose(finput);
-    if (!result && prefs->removeSrcFile) {  /* --rm */
+    if (!result && LZ4IO_mustRemoveSrcFile(prefs, input_filename)) {  /* --rm */
         if (remove(input_filename))
             END_PROCESS(45, "Remove error : %s: %s", input_filename, strerror(errno));
     }
diff --git a/tests/test-lz4-basic.sh b/tests/test-lz4-basic.sh
index 4fc411dc..125b680c 100755
--- a/tests/test-lz4-basic.sh
+++ b/tests/test-lz4-basic.sh
@@ -80,6 +80,17 @@ printf '\120\052\115\030\000\000\000\000BAD!' > $FPREFIX-bad.lz4
 cp $FPREFIX-bad.lz4 $FPREFIX-bad-before.lz4
 lz4 -d --rm -f $FPREFIX-bad.lz4 $FPREFIX-bad.out && exit 1
 diff -q $FPREFIX-bad-before.lz4 $FPREFIX-bad.lz4  # --rm keeps source after decoding failure
+echo "rm test" > $FPREFIX-rm
+lz4 $FPREFIX-rm $FPREFIX-rm.lz4
+cp $FPREFIX-rm.lz4 $FPREFIX-rm-before.lz4
+lz4 -t --rm $FPREFIX-rm.lz4
+diff -q $FPREFIX-rm-before.lz4 $FPREFIX-rm.lz4    # -t --rm keeps its input ("No files are created nor removed")
+lz4 -t --rm < $FPREFIX-rm.lz4                     # nothing to remove when reading stdin
+lz4 -c --rm < $FPREFIX-rm | lz4 -t                # idem when compressing
+lz4 -dc --rm < $FPREFIX-rm.lz4 | diff -q - $FPREFIX-rm  # idem when decompressing
+lz4 -d --rm $FPREFIX-rm.lz4 $FPREFIX-rm-out
+test ! -f $FPREFIX-rm.lz4                         # --rm still removes a regular source file
+test   -f $FPREFIX-rm-out
 lz4 -BX $FPREFIX-hw -c -q | lz4 -tv   # test block checksum
 # datagen -g20KB generates the same file every single time
 # cannot save output of datagen -g20KB as input file to lz4 because the following shell commands are run before datagen -g20KB

From ab7ec87f26654b09a9577197237de3ae3909ac09 Mon Sep 17 00:00:00 2001
From: Yann Collet <cyan@meta.com>
Date: Thu, 22 Oct 2026 16:09:26 -0700
Subject: [PATCH 2/2] NEWS: --rm skips -t and stdin

---
 NEWS | 1 +
 1 file changed, 1 insertion(+)

diff --git a/NEWS b/NEWS
index f4cab704..3a054c94 100644
--- a/NEWS
+++ b/NEWS
@@ -56,6 +56,7 @@ cli  : output buffer no longer grows with the nb of threads : more threads withi
 cli  : a source file modified, renamed or replaced during its compression is detected, and kept with `--rm` ; error 54 when the output can't be verified
 cli  : `lz4 -l` could hang on Windows with an empty input, as could decoding the resulting legacy stream
 cli  : `--rm` keeps the source file after a decompression failure, by @Furan666
+cli  : `lz4 -t --rm` no longer removes the tested file, and `--rm` with `stdin` no longer fails nor removes a file named `stdin`, by @Nexory
 cli  : `lz4 -t -m` no longer writes decoded content to stdout, reported by @tansy
 cli  : `lz4 --list` rejects truncated frames, instead of reporting them as valid, by @jmestwa-coder
 cli  : numeric arguments that overflow are rejected, instead of silently wrapping around, by @akashdeshmukh-git