Use spawnl() rather than pipe() & fork() to invoke xkbcomp

Implement System() specially on Cygwin not to use fork() and exec(), but
spawnl()

Use System() and a temp file rather than pipe() & fork() to invoke xkbcomp on
cygwin, just as done on mingw

Somewhat the counsel of despair, but sometimes Windows is being such a little
bitch that the cygwin DLL just can't emulate fork() successfully, so just using
spawnl() here is more robust and means I don't have to deal with end-users
reporting this as a problem with the xserver

Popen is not used, but must be built as it is referenced by sdksyms

v2: Update to include fix to Win32TempDir() when TMP is set but TEMP isn't

XXX: Really this should check TMPDIR first, as that's the canonical UNIX way to
set the temporary directory?

v3: Fix implicit-function-declaration of Win32TempDir() in XkbDDXCompileKeymapByNames()

Add a prototype for Win32TempDir()

Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>

3 files changed, 44 insertions, 7 deletions

diff --git a/include/os.h b/include/os.h
index b2b96c863..3f6e389e4 100644
--- a/include/os.h
+++ b/include/os.h
@@ -350,6 +350,10 @@ extern _X_EXPORT void *
 Fopen(const char *, const char *);
 extern _X_EXPORT int
 Fclose(void *);
+#if defined(__CYGWIN__)
+extern const char *
+Win32TempDir(void);
+#endif
 #else
 
 extern const char *
diff --git a/os/utils.c b/os/utils.c
index d09ca79fd..d2be119dd 100644
--- a/os/utils.c
+++ b/os/utils.c
@@ -1374,6 +1374,26 @@ OsAbort(void)
  * as well.  As it is now, xkbcomp messages don't end up in the log file.
  */
 
+#ifdef __CYGWIN__
+#include <process.h>
+int
+System(const char *command)
+{
+    int status;
+
+    if (!command)
+        return 1;
+
+    DebugF("System: `%s'\n", command);
+
+    /*
+       Use spawnl() rather than execl() to implement System() on cygwin to
+       avoid fork emulation overhead and brittleness
+     */
+    status = spawnl(_P_WAIT, "/bin/sh", "sh", "-c", command, (char *) NULL);
+    return status;
+}
+#else
 int
 System(const char *command)
 {
@@ -1416,6 +1436,7 @@ System(const char *command)
 
     return p == -1 ? -1 : status;
 }
+#endif
 
 static struct pid {
     struct pid *next;
@@ -1727,6 +1748,17 @@ System(const char *cmdline)
 
     return dwExitCode;
 }
+#elif defined(__CYGWIN__)
+const char*
+Win32TempDir(void)
+{
+    if (getenv("TEMP") != NULL)
+        return getenv("TEMP");
+    else if (getenv("TMP") != NULL)
+        return getenv("TMP");
+    else
+        return "/tmp";
+}
 #endif
 
 /*
diff --git a/xkb/ddxLoad.c b/xkb/ddxLoad.c
index f71815aa8..8955d913a 100644
--- a/xkb/ddxLoad.c
+++ b/xkb/ddxLoad.c
@@ -44,6 +44,7 @@ THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #include <xkbsrv.h>
 #include <X11/extensions/XI.h>
 #include "xkb.h"
+#include "os.h"
 
         /*
          * If XKM_OUTPUT_DIR specifies a path without a leading slash, it is
@@ -113,7 +114,7 @@ RunXkbComp(xkbcomp_buffer_callback callback, void *userdata)
     const char *xkbbindir = emptystring;
     const char *xkbbindirsep = emptystring;
 
-#ifdef WIN32
+#if defined(WIN32) || defined(__CYGWIN__)
     /* WIN32 has no popen. The input must be stored in a file which is
        used as input for xkbcomp. xkbcomp does not read from stdin. */
     char tmpname[PATH_MAX];
@@ -126,9 +127,9 @@ RunXkbComp(xkbcomp_buffer_callback callback, void *userdata)
 
     OutputDirectory(xkm_output_dir, sizeof(xkm_output_dir));
 
-#ifdef WIN32
+#if defined(WIN32) || defined(__CYGWIN__)
     strcpy(tmpname, Win32TempDir());
-    strcat(tmpname, "\\xkb_XXXXXX");
+    strcat(tmpname, PATHSEPARATOR "xkb_XXXXXX");
     (void) mktemp(tmpname);
 #endif
 
@@ -167,7 +168,7 @@ RunXkbComp(xkbcomp_buffer_callback callback, void *userdata)
         return NULL;
     }
 
-#ifndef WIN32
+#if !defined(WIN32) && !defined(__CYGWIN__)
     out = Popen(buf, "w");
 #else
     out = fopen(tmpname, "w");
@@ -177,7 +178,7 @@ RunXkbComp(xkbcomp_buffer_callback callback, void *userdata)
         /* Now write to xkbcomp */
         (*callback)(out, userdata);
 
-#ifndef WIN32
+#if !defined(WIN32) && !defined(__CYGWIN__)
         if (Pclose(out) == 0)
 #else
         if (fclose(out) == 0 && System(buf) >= 0)
@@ -186,14 +187,14 @@ RunXkbComp(xkbcomp_buffer_callback callback, void *userdata)
             if (xkbDebugFlags)
                 DebugF("[xkb] xkb executes: %s\n", buf);
             free(buf);
-#ifdef WIN32
+#if defined(WIN32) || defined(__CYGWIN__)
             unlink(tmpname);
 #endif
             return xnfstrdup(keymap);
         }
         else
             LogMessage(X_ERROR, "Error compiling keymap (%s)\n", keymap);
-#ifdef WIN32
+#if defined(WIN32) || defined(__CYGWIN__)
         /* remove the temporary file */
         unlink(tmpname);
 #endif