From e5d96ca630bac3b37abfe70963ff5436ecc1f21c Mon Sep 17 00:00:00 2001
From: Paulo Zanoni <pzanoni@mandriva.com>
Date: Tue, 1 Mar 2011 10:58:16 -0300
Subject: [PATCH 908/908] XKB: cache xkbcomp output for fast start-up v.1 for 1.10.0

The patch stores the cached files inside /usr/share/X11/xkb/compiled.
This should save ~0.6 seconds at each boot.

This patch is a new version of the patch written by Yan Li and used
in Moblin 1.6. Moblin's patch is based on pcpa's patch.

pcpa's patch had ~1100 line changes, while this one has ~200 changes,
so it should be easier to port to newer versions.

I really hope we deprecate this patch soon! (libxkbcommon??)
---
 xkb/README.compiled |    8 +-
 xkb/ddxLoad.c       |  192 ++++++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 162 insertions(+), 38 deletions(-)

diff --git a/xkb/README.compiled b/xkb/README.compiled
index 71caa2f..a4a2ae0 100644
--- a/xkb/README.compiled
+++ b/xkb/README.compiled
@@ -4,10 +4,10 @@ current keymap and/or any scratch keymaps used by clients.  The X server
 or some other tool might destroy or replace the files in this directory,
 so it is not a safe place to store compiled keymaps for long periods of
 time.  The default keymap for any server is usually stored in:
-     X<num>-default.xkm
-where <num> is the display number of the server in question, which makes
-it possible for several servers *on the same host* to share the same 
-directory.
+     server-<SHA1>.xkm
+
+where <SHA1> is the SHA1 hash of keymap source, so that compiled
+keymap of different keymap sources are stored in different files.
 
 Unless the X server is modified, sharing this directory between servers on
 different hosts could cause problems.
diff --git a/xkb/ddxLoad.c b/xkb/ddxLoad.c
index ac587fc..dd4b13d 100644
--- a/xkb/ddxLoad.c
+++ b/xkb/ddxLoad.c
@@ -30,6 +30,13 @@ THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 #include <xkb-config.h>
 
+#ifdef HAVE_SHA1_IN_LIBMD /* Use libmd for SHA1 */
+# include <sha1.h>
+#else /* Use OpenSSL's libcrypto */
+# include <stddef.h>  /* buggy openssl/sha.h wants size_t */
+# include <openssl/sha.h>
+#endif
+
 #include <stdio.h>
 #include <ctype.h>
 #include <X11/X.h>
@@ -43,20 +50,9 @@ THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #define	XKBSRV_NEED_FILE_FUNCS
 #include <xkbsrv.h>
 #include <X11/extensions/XI.h>
+#include <errno.h>
 #include "xkb.h"
 
-	/*
-	 * If XKM_OUTPUT_DIR specifies a path without a leading slash, it is
-	 * relative to the top-level XKB configuration directory.
-	 * Making the server write to a subdirectory of that directory
-	 * requires some work in the general case (install procedure
-	 * has to create links to /var or somesuch on many machines),
-	 * so we just compile into /usr/tmp for now.
-	 */
-#ifndef XKM_OUTPUT_DIR
-#define	XKM_OUTPUT_DIR	"compiled/"
-#endif
-
 #define	PRE_ERROR_MSG "\"The XKEYBOARD keymap compiler (xkbcomp) reports:\""
 #define	ERROR_PREFIX	"\"> \""
 #define	POST_ERROR_MSG1 "\"Errors from xkbcomp are not fatal to the X server\""
@@ -171,6 +167,45 @@ OutputDirectory(
 }
 
 static Bool
+Sha1Asc(char sha1Asc[SHA_DIGEST_LENGTH*2+1], const char * input)
+{
+    int i;
+    unsigned char sha1[SHA_DIGEST_LENGTH];
+
+#ifdef HAVE_SHA1_IN_LIBMD /* Use libmd for SHA1 */
+    SHA1_CTX ctx;
+
+    SHA1Init (&ctx);
+    SHA1Update (&ctx, input, strlen(input));
+    SHA1Final (sha1, &ctx);
+#else /* Use OpenSSL's libcrypto */
+    SHA_CTX ctx;
+    int success;
+
+    success = SHA1_Init (&ctx);
+    if (! success)
+       return BadAlloc;
+
+    success = SHA1_Update (&ctx, input, strlen(input));
+    if (! success)
+       return BadAlloc;
+
+    success = SHA1_Final (sha1, &ctx);
+    if (! success)
+       return BadAlloc;
+#endif
+
+    /* convert sha1 to sha1_asc */
+    for(i=0; i<SHA_DIGEST_LENGTH; ++i) {
+        sprintf(sha1Asc+i*2, "%02X", sha1[i]);
+    }
+
+    return Success;
+}
+
+/* call xkbcomp and compile XKB keymap, return xkm file name in
+   nameRtrn */
+static Bool
 XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
 				XkbComponentNamesPtr	names,
 				unsigned		want,
@@ -179,7 +214,12 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
 				int			nameRtrnLen)
 {
     FILE *	out;
-    char	*buf = NULL, keymap[PATH_MAX], xkm_output_dir[PATH_MAX];
+    char *     buf = NULL, xkmfile[PATH_MAX], xkm_output_dir[PATH_MAX];
+    char *     tmpXkmFile = NULL;
+    char *     canonicalXkmFileName = NULL;
+    char       sha1Asc[SHA_DIGEST_LENGTH*2+1], xkbKeyMapBuf[100*1024];
+    int        ret, result;
+
 
     const char	*emptystring = "";
     char *xkbbasedirflag = NULL;
@@ -190,15 +230,70 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
     /* 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];
-    const char *xkmfile = tmpname;
+    const char *xkbfile = tmpname;
 #else
-    const char *xkmfile = "-";
+    const char *xkbfile = "-";
+#endif
+
+    /* Write keymap source (xkbfile) to memory buffer `xkbKeyMapBuf',
+       of which SHA1 is generated and used as result xkm file name  */
+    memset(xkbKeyMapBuf, 0, sizeof(xkbKeyMapBuf));
+    out = fmemopen(xkbKeyMapBuf, sizeof(xkbKeyMapBuf), "w");
+    if (NULL == out) {
+        ErrorF("[xkb] Open xkbKeyMapBuf for writing failed\n");
+        return FALSE;
+    }
+    ret = XkbWriteXKBKeymapForNames(out, names, xkb, want, need);
+    if (fclose(out) !=0)
+    {
+        ErrorF("[xkb] XkbWriteXKBKeymapForNames error, perhaps xkbKeyMapBuf is too small\n");
+        return FALSE;
+    }
+#ifdef DEBUG
+    if (xkbDebugFlags) {
+       ErrorF("[xkb] XkbDDXCompileKeymapByNames compiling keymap:\n");
+       fputs(xkbKeyMapBuf, stderr);
+    }
 #endif
+    if (!ret) {
+        ErrorF("[xkb] Generating XKB Keymap failed, giving up compiling keymap\n");
+        return FALSE;
+    }
 
-    snprintf(keymap, sizeof(keymap), "server-%s", display);
+    DebugF("[xkb] computing SHA1 of keymap\n");
+    if (Success == Sha1Asc(sha1Asc, xkbKeyMapBuf)) {
+        snprintf(xkmfile, sizeof(xkmfile), "server-%s", sha1Asc);
+    }
+    else {
+        ErrorF("[xkb] Computing SHA1 of keymap failed, "
+               "using display name instead as xkm file name\n");
+        snprintf(xkmfile, sizeof(xkmfile), "server-%s", display);
+    }
 
+    /* XkbEnsureSafeMapName(xkmfile); */
     OutputDirectory(xkm_output_dir, sizeof(xkm_output_dir));
 
+    /* set nameRtrn, fail if it's too small */
+    if ((strlen(xkmfile)+1 > nameRtrnLen) && nameRtrn) {
+        ErrorF("[xkb] nameRtrn too small to hold xkmfile name\n");
+        return FALSE;
+    }
+    strncpy(nameRtrn, xkmfile, nameRtrnLen);
+
+    /* if the xkm file already exists, reuse it */
+    canonicalXkmFileName = Xprintf("%s%s.xkm", xkm_output_dir, xkmfile);
+    if (access(canonicalXkmFileName, R_OK) == 0) {
+        /* yes, we can reuse the old xkm file */
+        LogMessage(X_INFO, "XKB: reuse xkmfile %s\n", canonicalXkmFileName);
+        result = TRUE;
+        goto _ret;
+    }
+    LogMessage(X_INFO, "XKB: generating xkmfile %s\n", canonicalXkmFileName);
+
+    /* continue to call xkbcomp to compile the keymap. to avoid race
+       condition, we compile it to a tmpfile then rename it to
+       xkmfile */
+
 #ifdef WIN32
     strcpy(tmpname, Win32TempDir());
     strcat(tmpname, "\\xkb_XXXXXX");
@@ -222,15 +317,27 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
 	}
     }
 
+   /* tmpXkmFile will be moved to xkm_output_dir using rename(2), which doesn't
+    * work between multiple file systems, so we better generate the temporary
+    * file inside xkm_output_dir
+    * This temporary file is used to prevent race conditions (multiple
+    * Xservers), so we use the display string on its name to guarantee that
+    * concurrent Xservers won't use the same tmpfile name */
+   if (asprintf(&tmpXkmFile, "%s/tmp-%s.xkm", xkm_output_dir, display) == -1) {
+       ErrorF("[xkb] Can't generate temp xkm file name");
+       result = FALSE;
+       goto _ret;
+   }
+
     if (asprintf(&buf,
 		 "\"%s%sxkbcomp\" -w %d %s -xkm \"%s\" "
-		  "-em1 %s -emp %s -eml %s \"%s%s.xkm\"",
+		  "-em1 %s -emp %s -eml %s \"%s\"",
 		 xkbbindir, xkbbindirsep,
 		 ((xkbDebugFlags < 2) ? 1 :
 		  ((xkbDebugFlags > 10) ? 10 : (int) xkbDebugFlags)),
-		 xkbbasedirflag ? xkbbasedirflag : "", xkmfile,
+		 xkbbasedirflag ? xkbbasedirflag : "", xkbfile,
 		 PRE_ERROR_MSG, ERROR_PREFIX, POST_ERROR_MSG1,
-		 xkm_output_dir, keymap) == -1)
+		 tmpXkmFile) == -1)
 	buf = NULL;
 
     free(xkbbasedirflag);
@@ -247,30 +354,41 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
 #endif
     
     if (out!=NULL) {
-#ifdef DEBUG
-    if (xkbDebugFlags) {
-       ErrorF("[xkb] XkbDDXCompileKeymapByNames compiling keymap:\n");
-       XkbWriteXKBKeymapForNames(stderr,names,xkb,want,need);
-    }
-#endif
-	XkbWriteXKBKeymapForNames(out,names,xkb,want,need);
+       /* write XKBKeyMapBuf to xkbcomp */
+       if (EOF==fputs(xkbKeyMapBuf, out))
+       {
+           ErrorF("[xkb] Sending keymap to xkbcomp failed\n");
+           result = FALSE;
+           goto _ret;
+        }
 #ifndef WIN32
 	if (Pclose(out)==0)
 #else
 	if (fclose(out)==0 && System(buf) >= 0)
 #endif
 	{
+	    /* xkbcomp success */
             if (xkbDebugFlags)
                 DebugF("[xkb] xkb executes: %s\n",buf);
-	    if (nameRtrn) {
-		strncpy(nameRtrn,keymap,nameRtrnLen);
-		nameRtrn[nameRtrnLen-1]= '\0';
+           /* if canonicalXkmFileName already exists now, we simply
+              overwrite it, this is OK */
+           ret = rename(tmpXkmFile, canonicalXkmFileName);
+           if (0 != ret) {
+               ErrorF("[xkb] Can't rename %s to %s, error: %s\n",
+                      tmpXkmFile, canonicalXkmFileName,
+                      strerror(errno));
+
+               /* in case of error, don't unlink tmpXkmFile, leave it
+                  for debugging */
+
+               result = FALSE;
+               goto _ret;
 	    }
-            free(buf);
-	    return TRUE;
+	    result = TRUE;
+            goto _ret;
 	}
 	else
-	    LogMessage(X_ERROR, "Error compiling keymap (%s)\n", keymap);
+	    LogMessage(X_ERROR, "Error compiling keymap (%s)\n", xkbfile);
 #ifdef WIN32
         /* remove the temporary file */
         unlink(tmpname);
@@ -285,8 +403,15 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
     }
     if (nameRtrn)
 	nameRtrn[0]= '\0';
+
+    result = FALSE;
+_ret:
+    if (tmpXkmFile)
+	free(tmpXkmFile);
+    if (canonicalXkmFileName)
+	xfree(canonicalXkmFileName);
     free(buf);
-    return FALSE;
+    return result;
 }
 
 static FILE *
@@ -363,7 +488,6 @@ unsigned	missing;
     if (*xkbRtrn==NULL) {
 	LogMessage(X_ERROR, "Error loading keymap %s\n",fileName);
 	fclose(file);
-	(void) unlink (fileName);
 	return 0;
     }
     else {
-- 
1.7.1