[PATCH] Patch to not fork/exec xkbcomp on X Server initialization

Peter Hutterer peter.hutterer at who-t.net
Thu Mar 26 18:17:14 PDT 2009


On Wed, Mar 25, 2009 at 02:58:36PM +0800, Li, Yan wrote:
> This is the patch that I wrote for Moblin as part of the efforts of
> fast-boot to save some load time of X server: xkbcomp outputs will be
> cached in files with hashed keymap as names (using SHA1). This saves
> boot time for around 1s on commodity netbooks.  It is made against
> 1.6.0.
> 
> I haven't read Paulo's latest patch that uses SHA1 as file names until
> I've finished my own (though I do have read early versions of his
> patch).  Interestingly that we've employed similar idea.
> 
> Comparing to Paulo's patch, this one is much simpler, with the goal
> that touch as few things as possible. And xkbcomp's output will be
> stored in /var/lib/xkb/ instead of somewhere under /usr/.

I think /var/cache instead of /var/lib is the better place to put the files.
http://www.pathname.com/fhs/pub/fhs-2.3.html#VARLIBVARIABLESTATEINFORMATION
vs.
http://www.pathname.com/fhs/pub/fhs-2.3.html#VARCACHEAPPLICATIONCACHEDATA

> In this patch there are also corrections to wrongly used TAB for
> indention of codes related to this function. If you don't like it I
> can move them to another standalone patch.

Yes, please always do things like that (if needed at all) in a separate patch.
If you correct tab/space issues in the code you're modifying it doesn't
matter much, but this patch is quite noisy.

> I understood the difficulty of merging functions like this into
> mainstream. Or if we need to add an option to make this behaviour
> optional, rather than enabled by default.  I'd like to follow on this
> until people is happy with it.

It's looking good from a first pass, but I'd really like to see the patches
split into one containing just the actual changes. I'm happy to test it then.

Cheers,
  Peter

> From e7046c26d7ac970bfd75cae16262845bef72423b Mon Sep 17 00:00:00 2001
> From: Yan Li <yan.i.li at intel.com>
> Date: Tue, 24 Mar 2009 17:43:12 +0800
> Subject: [PATCH] Cache xkbcomp output for fast start-up
> 
> xkbcomp outputs will be cached in files with hashed keymap as
> names. This saves boot time for around 1s on commodity netbooks.
> 
> Signed-off-by: Yan Li <yan.i.li at intel.com>
> ---
>  xkb/ddxLoad.c  |  188 +++++++++++++++++++++++++++++++++++++++++---------------
>  xkb/xkbfmisc.c |   18 +++++-
>  2 files changed, 153 insertions(+), 53 deletions(-)
> 
> diff --git a/xkb/ddxLoad.c b/xkb/ddxLoad.c
> index 4d5dfb6..799622d 100644
> --- a/xkb/ddxLoad.c
> +++ b/xkb/ddxLoad.c
> @@ -32,6 +32,12 @@ THE USE OR PERFORMANCE OF THIS SOFTWARE.
>  #include <xkb-config.h>
>  #endif
>  
> +#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>
>  #define	NEED_EVENTS 1
> @@ -159,25 +165,61 @@ OutputDirectory(
>      size_t size)
>  {
>  #ifndef WIN32
> -    if (getuid() == 0 && (strlen(XKM_OUTPUT_DIR) < size))
> -    {
> -	/* if server running as root it *may* be able to write */
> -	/* FIXME: check whether directory is writable at all */
> -	(void) strcpy (outdir, XKM_OUTPUT_DIR);
> +    if (getuid() == 0 && (strlen(XKM_OUTPUT_DIR) < size)) {
> +        /* if server running as root it *may* be able to write */
> +        /* FIXME: check whether directory is writable at all */
> +        (void) strcpy (outdir, XKM_OUTPUT_DIR);
>      } else
>  #else
> -    if (strlen(Win32TempDir()) + 1 < size)
> -    {
> -	(void) strcpy(outdir, Win32TempDir());
> -	(void) strcat(outdir, "\\");
> +    if (strlen(Win32TempDir()) + 1 < size) {
> +        (void) strcpy(outdir, Win32TempDir());
> +        (void) strcat(outdir, "\\");
>      } else 
>  #endif
> -    if (strlen("/tmp/") < size)
> -    {
> -	(void) strcpy (outdir, "/tmp/");
> +    if (strlen("/tmp/") < size) {
> +        (void) strcpy (outdir, "/tmp/");
> +    }
> +}
> +
> +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,
> @@ -187,7 +229,9 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
>  				int			nameRtrnLen)
>  {
>      FILE *	out;
> -    char	*buf = NULL, keymap[PATH_MAX], xkm_output_dir[PATH_MAX];
> +    char *	buf = NULL, xkmfile[PATH_MAX], xkmOutputDir[PATH_MAX];
> +    char	sha1Asc[SHA_DIGEST_LENGTH*2+1], xkbKeyMapBuf[1024];
> +    int	ret;
>  
>      const char	*emptystring = "";
>      const char	*xkbbasedirflag = emptystring;
> @@ -198,15 +242,58 @@ 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
> +    char *	canonicalXkmfileName;
> +
> +    /* Write XKBKeyMap (xkbfile contents) to xkbKeyMapBuf, of which
> +       SHA1 is generated as XKB file name  */
> +    memset(xkbKeyMapBuf, 0, sizeof(xkbKeyMapBuf));
> +    out = fmemopen(xkbKeyMapBuf, sizeof(xkbKeyMapBuf), "w");
> +    if (NULL == out) {
> +        ErrorF("[xkb] open xkbKeyMapBuf for writting\n");
> +        return False;
> +    }
> +    ret = XkbWriteXKBKeymapForNames(out, names, xkb, want, need);
> +    fclose(out);
> +    if (!ret) {
> +        ErrorF("[xkb] generating XKB Keymap, giving up compiling Keymap\n");
> +        return False;
> +    }
> +    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, using display name instead\n");
> +        snprintf(xkmfile, sizeof(xkmfile), "server-%s", display);
> +    }
>  
> -    snprintf(keymap, sizeof(keymap), "server-%s", display);
> +    XkbEnsureSafeMapName(xkmfile);
> +    OutputDirectory(xkmOutputDir, sizeof(xkmOutputDir));
> +
> +    /* 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 xkb file already exists, reuse it */
> +    canonicalXkmfileName = Xprintf("%s%s.xkm", xkmOutputDir, xkmfile);
> +    LogMessage(X_INFO, "[xkb] xkmfile %s ", canonicalXkmfileName);
> +    if (access(canonicalXkmfileName, R_OK) == 0) {
> +        /* yes, we can reuse old xkb file */
> +        LogMessage(X_INFO, "reused\n");
> +        xfree(canonicalXkmfileName);
> +        return True;
> +    }
> +    LogMessage(X_INFO, "is being compiled\n");
> +    xfree(canonicalXkmfileName);
>  
> -    XkbEnsureSafeMapName(keymap);
> -    OutputDirectory(xkm_output_dir, sizeof(xkm_output_dir));
> +    /* continue to call xkbcomp to compile the keymap */
>  
>  #ifdef WIN32
>      strcpy(tmpname, Win32TempDir());
> @@ -215,19 +302,19 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
>  #endif
>  
>      if (XkbBaseDirectory != NULL) {
> -	xkbbasedirflag = Xprintf("\"-R%s\"", XkbBaseDirectory);
> +        xkbbasedirflag = Xprintf("\"-R%s\"", XkbBaseDirectory);
>      }
>  
>      if (XkbBinDirectory != NULL) {
> -	int ld = strlen(XkbBinDirectory);
> -	int lps = strlen(PATHSEPARATOR);
> +        int ld = strlen(XkbBinDirectory);
> +        int lps = strlen(PATHSEPARATOR);
>  
> -	xkbbindir = XkbBinDirectory;
> +        xkbbindir = XkbBinDirectory;
>  
> -	if ((ld >= lps) &&
> -	    (strcmp(xkbbindir + ld - lps, PATHSEPARATOR) != 0)) {
> -	    xkbbindirsep = PATHSEPARATOR;
> -	}
> +        if ((ld >= lps) &&
> +            (strcmp(xkbbindir + ld - lps, PATHSEPARATOR) != 0)) {
> +            xkbbindirsep = PATHSEPARATOR;
> +        }
>      }
>  
>      buf = Xprintf("\"%s%sxkbcomp\" -w %d %s -xkm \"%s\" "
> @@ -235,12 +322,12 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
>  		  xkbbindir, xkbbindirsep,
>  		  ( (xkbDebugFlags < 2) ? 1 :
>  		    ((xkbDebugFlags > 10) ? 10 : (int)xkbDebugFlags) ),
> -		  xkbbasedirflag, xkmfile,
> +		  xkbbasedirflag, xkbfile,
>  		  PRE_ERROR_MSG, ERROR_PREFIX, POST_ERROR_MSG1,
> -		  xkm_output_dir, keymap);
> +		  xkmOutputDir, xkmfile);
>  
>      if (xkbbasedirflag != emptystring) {
> -	xfree(xkbbasedirflag);
> +        xfree(xkbbasedirflag);
>      }
>      
>  #ifndef WIN32
> @@ -248,33 +335,34 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
>  #else
>      out= fopen(tmpname, "w");
>  #endif
> -    
> +
>      if (out!=NULL) {
>  #ifdef DEBUG
> -    if (xkbDebugFlags) {
> -       ErrorF("[xkb] XkbDDXCompileKeymapByNames compiling keymap:\n");
> -       XkbWriteXKBKeymapForNames(stderr,names,xkb,want,need);
> -    }
> +        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\n");
> +            return False;
> +        }
>  #ifndef WIN32
> -	if (Pclose(out)==0)
> +        if (Pclose(out)==0) {
>  #else
> -	if (fclose(out)==0 && System(buf) >= 0)
> +        if (fclose(out)==0 && System(buf) >= 0) {
>  #endif
> -	{
>              if (xkbDebugFlags)
>                  DebugF("[xkb] xkb executes: %s\n",buf);
> -	    if (nameRtrn) {
> -		strncpy(nameRtrn,keymap,nameRtrnLen);
> -		nameRtrn[nameRtrnLen-1]= '\0';
> -	    }
>              if (buf != NULL)
>                  xfree (buf);
> -	    return True;
> -	}
> -	else
> -	    LogMessage(X_ERROR, "Error compiling keymap (%s)\n", keymap);
> +            return True;
> +        }
> +        else
> +            LogMessage(X_ERROR, "Error compiling keymap (%s)\n", xkbfile);
> +
>  #ifdef WIN32
>          /* remove the temporary file */
>          unlink(tmpname);
> @@ -282,13 +370,14 @@ XkbDDXCompileKeymapByNames(	XkbDescPtr		xkb,
>      }
>      else {
>  #ifndef WIN32
> -	LogMessage(X_ERROR, "XKB: Could not invoke xkbcomp\n");
> +        LogMessage(X_ERROR, "XKB: Could not invoke xkbcomp\n");
>  #else
> -	LogMessage(X_ERROR, "Could not open file %s\n", tmpname);
> +        LogMessage(X_ERROR, "Could not open file %s\n", tmpname);
>  #endif
>      }
> +
>      if (nameRtrn)
> -	nameRtrn[0]= '\0';
> +        nameRtrn[0]= '\0';
>      if (buf != NULL)
>          xfree (buf);
>      return False;
> @@ -375,7 +464,6 @@ unsigned	missing;
>  	DebugF("Loaded XKB keymap %s, defined=0x%x\n",fileName,(*xkbRtrn)->defined);
>      }
>      fclose(file);
> -    (void) unlink (fileName);
>      return (need|want)&(~missing);
>  }
>  
> diff --git a/xkb/xkbfmisc.c b/xkb/xkbfmisc.c
> index ae752e9..5abf3c7 100644
> --- a/xkb/xkbfmisc.c
> +++ b/xkb/xkbfmisc.c
> @@ -293,15 +293,27 @@ unsigned	wantNames,wantConfig,wantDflts;
>      multi_section= 1;
>      if (((complete&XkmKeymapRequired)==XkmKeymapRequired)&&
>  	((complete&(~XkmKeymapLegal))==0)) {
> -	fprintf(file,"xkb_keymap \"%s\" {\n",name);
> +        if (fprintf(file,"xkb_keymap \"%s\" {\n",name) <= 0)
> +        {
> +            ErrorF("[xkb] writting XKB Keymap\n");
> +            return False;
> +        }
>      }
>      else if (((complete&XkmSemanticsRequired)==XkmSemanticsRequired)&&
>  	((complete&(~XkmSemanticsLegal))==0)) {
> -	fprintf(file,"xkb_semantics \"%s\" {\n",name);
> +        if (fprintf(file,"xkb_semantics \"%s\" {\n",name)<=0)
> +        {
> +            ErrorF("[xkb] writting XKB Keymap\n");
> +            return False;
> +        }
>      }
>      else if (((complete&XkmLayoutRequired)==XkmLayoutRequired)&&
>  	((complete&(~XkmLayoutLegal))==0)) {
> -	fprintf(file,"xkb_layout \"%s\" {\n",name);
> +        if (fprintf(file,"xkb_layout \"%s\" {\n",name)<=0)
> +        {
> +            ErrorF("[xkb] writting XKB Keymap\n");
> +            return False;
> +        }
>      }
>      else if (XkmSingleSection(complete&(~XkmVirtualModsMask))) {
>  	multi_section= 0;
> -- 
> 1.5.6.5
> 



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