[PATCH libXpm] open-zfile: Make compress & uncompress commands optional

[Alan Coopersmith]

If compress is not found, we disable writing to .Z files,
but leave the rest of the compression code active.

If uncompress is not found, we use gzip to read .Z files.

Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
---

For those who don't watch gitlab MR's, this is submitted as
https://gitlab.freedesktop.org/xorg/lib/libxpm/-/merge_requests/14

 configure.ac    | 17 ++++++++++++-----
 src/RdFToI.c    |  4 ++++
 src/WrFFrI.c    |  4 ++++
 test/XpmWrite.c | 23 +++++++++++++++++++++++
 4 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index 61a5f08..60f959c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -52,9 +52,8 @@ AM_CONDITIONAL(USE_GETTEXT, test "x$USE_GETTEXT" = "xyes")
 dnl Helper macro to find absolute path to program and add a #define for it
 AC_DEFUN([XPM_PATH_PROG],[
 AC_PATH_PROG([$1], [$2], [])
-AS_IF([test "x$$1" = "x"],
-      [AC_MSG_ERROR([$2 not found, set $1 or use --disable-open-zfile])])
-AC_DEFINE_UNQUOTED([$1], ["$$1"], [Path to $2])
+AS_IF([test "x$$1" = "x"], [$3],
+      [AC_DEFINE_UNQUOTED([$1], ["$$1"], [Path to $2])])
 ]) dnl End of AC_DEFUN([XPM_PATH_PROG]...
 
 # Optional feature: When a filename ending in .Z or .gz is requested,
@@ -74,9 +73,17 @@ AM_CONDITIONAL(COMPRESSED_PIXMAPS, test "x$OPEN_ZFILE" = "xyes")
 if test x$OPEN_ZFILE = xno ; then
         AC_DEFINE(NO_ZPIPE, 1, [Define to 1 to disable decompression via pipes])
 else
-        XPM_PATH_PROG([XPM_PATH_COMPRESS], [compress])
+        # gzip is absolutely required for the compressed file handling code
+        XPM_PATH_PROG([XPM_PATH_GZIP], [gzip],
+            [AC_MSG_ERROR([gzip not found, set XPM_PATH_GZIP or use --disable-open-zfile])])
+
+        # if compress is not found, we disable writing to .Z files,
+        # but leave the rest of the compression code active
+        XPM_PATH_PROG([XPM_PATH_COMPRESS], [compress],
+            [AC_MSG_WARN([compress not found, disabling writing of .Z files])])
+        # if uncompress is not found, we use gzip to read .Z files
         XPM_PATH_PROG([XPM_PATH_UNCOMPRESS], [uncompress])
-        XPM_PATH_PROG([XPM_PATH_GZIP], [gzip])
+
         AC_CHECK_FUNCS([closefrom close_range], [break])
 fi
 
diff --git a/src/RdFToI.c b/src/RdFToI.c
index 141c485..a16af88 100644
--- a/src/RdFToI.c
+++ b/src/RdFToI.c
@@ -246,7 +246,11 @@ OpenReadFile(
 	if ( ext && !strcmp(ext, ".Z") )
 	{
 	    mdata->type = XPMPIPE;
+#ifdef XPM_PATH_UNCOMPRESS
 	    mdata->stream.file = xpmPipeThrough(fd, XPM_PATH_UNCOMPRESS, "-c", "r");
+#else
+	    mdata->stream.file = xpmPipeThrough(fd, XPM_PATH_GZIP, "-dqc", "r");
+#endif
 	}
 	else if ( ext && !strcmp(ext, ".gz") )
 	{
diff --git a/src/WrFFrI.c b/src/WrFFrI.c
index d59098f..234197a 100644
--- a/src/WrFFrI.c
+++ b/src/WrFFrI.c
@@ -342,7 +342,11 @@ OpenWriteFile(
 #ifndef NO_ZPIPE
 	len = strlen(filename);
 	if (len > 2 && !strcmp(".Z", filename + (len - 2))) {
+#ifdef XPM_PATH_COMPRESS
 	    mdata->stream.file = xpmPipeThrough(fd, XPM_PATH_COMPRESS, NULL, "w");
+#else
+	    mdata->stream.file = NULL;
+#endif
 	    mdata->type = XPMPIPE;
 	} else if (len > 3 && !strcmp(".gz", filename + (len - 3))) {
 	    mdata->stream.file = xpmPipeThrough(fd, XPM_PATH_GZIP, "-q", "w");
diff --git a/test/XpmWrite.c b/test/XpmWrite.c
index 53e010e..10b6207 100644
--- a/test/XpmWrite.c
+++ b/test/XpmWrite.c
@@ -59,6 +59,22 @@ is_compressed(const char *filepath)
     return FALSE;
 }
 
+/*
+ * If a filename ends in ".Z" or ".gz", remove that extension to avoid
+ * confusing libXpm into applying compression when not desired.
+ */
+static inline void
+strip_compress_ext(char *filepath)
+{
+    char *ext = strrchr(filepath, '.');
+
+    if ((ext != NULL) &&
+        (((ext[1] == 'Z') && (ext[2] == 0)) ||
+         ((ext[1] == 'g') && (ext[2] == 'z') && (ext[3] == 0)))) {
+        *ext = '\0';
+    }
+}
+
 /*
  * XpmWriteFileFromXpmImage - Write XPM files without requiring an X Display
   */
@@ -114,6 +130,7 @@ TestWriteFileFromXpmImage(const gchar *filepath)
     g_assert_no_error(err);
 
     filename = g_path_get_basename(filepath);
+    strip_compress_ext(filename);
     newfilepath = g_build_filename(testdir, filename, NULL);
 
     test_WFFXI_helper(newfilepath, &imageA, &infoA);
@@ -123,9 +140,11 @@ TestWriteFileFromXpmImage(const gchar *filepath)
     test_WFFXI_helper(cmpfilepath, &imageA, &infoA);
     g_free(cmpfilepath);
 
+#ifdef XPM_PATH_COMPRESS
     cmpfilepath = g_strdup_printf("%s.Z", newfilepath);
     test_WFFXI_helper(cmpfilepath, &imageA, &infoA);
     g_free(cmpfilepath);
+#endif
 #endif
 
     XpmFreeXpmImage(&imageA);
@@ -203,6 +222,7 @@ TestWriteFileFromData(const gchar *filepath)
     g_assert_no_error(err);
 
     filename = g_path_get_basename(filepath);
+    strip_compress_ext(filename);
     newfilepath = g_build_filename(testdir, filename, NULL);
 
     test_WFFXD_helper(newfilepath, data);
@@ -212,9 +232,11 @@ TestWriteFileFromData(const gchar *filepath)
     test_WFFXD_helper(cmpfilepath, data);
     g_free(cmpfilepath);
 
+#ifdef XPM_PATH_COMPRESS
     cmpfilepath = g_strdup_printf("%s.Z", newfilepath);
     test_WFFXD_helper(cmpfilepath, data);
     g_free(cmpfilepath);
+#endif
 #endif
 
     XpmFree(data);
@@ -259,6 +281,7 @@ TestWriteFileFromBuffer(const gchar *filepath)
     g_assert_no_error(err);
 
     filename = g_path_get_basename(filepath);
+    strip_compress_ext(filename);
     newfilepath = g_build_filename(testdir, filename, NULL);
     g_test_message("...writing %s", newfilepath);
 
-- 
2.15.2