[ccache] [PATCH] flag for using relative directories

[yince]

Hi, I'm new to ccache and was asking myself the question:
how ccache handles the -I directives.

Your solution is good.
I tough ccache would ignore the -I option since it affects 
only the preprocessor  and ccache use it to build the hash.

Would it be correct and safe to have an option to ignore -I option ?

Regards,
Vincent


Andrea Bittau wrote:
> 
> It is common for developers in a shared environment to compile the same
> code, but in a different location [e.g. their home] and furthermore, to
> use absolute path-names in their includes flags.  This results in two
> different outputs from the preprocessor, even though the same file is
> included [just different path], making it impossible to share a cache.
> CCACHE_UNIFY could be used to get rid of the comments from the
> preprocessor, but the problem here is of different nature: we do not
> wish to UNIFY, and have side-effects such as wrong line information, but
> rather just use relative paths so that the output of two preprocesses is
> the same.
> 
> I've added a new boolean, CCACHE_RELATIVE that will modify all the -I
> flags to be relative directories from where ccache is called.  An
> absolute pathname will be retained if the "common root" between the
> working directory and the included path is "/".  For example, the
> following command line:
> /home/sorbo$ gcc -I/common/stuff -I/home/sorbo/includes
> will be translated to:
> /home/sorbo$ gcc -I/common/stuff -Iincludes
> 
> Please consider applying this patch or implementing similar
> functionality.  This scenario is very common in many work places.  The
> patch is against ccache v2.4.
> 
> This has discussed on this mailing list to some extent, but I am unable
> to see attached patches from the web archive, so I had to code something
> myself.  Also, I don't know what happened to the proposed patches, so I
> just redid the work.  References:
> 
> 1) Steve Bennet "[ccache] [PATCH] Better cache reuse across builds in
> separate trees":
> http://lists.samba.org/archive/ccache/2005q2/000167.html
> 
> 2) Chris Swiedler "[ccache] ccache and -g"
> http://lists.samba.org/archive/ccache/2006q1/000201.html
> 
> ---
> 
> diff -rup ccache-2.4.orig/ccache.c ccache-2.4/ccache.c
> --- ccache-2.4.orig/ccache.c	2004-09-13 11:38:30.000000000 +0100
> +++ ccache-2.4/ccache.c	2007-06-18 15:10:05.000000000 +0100
> @@ -615,6 +615,119 @@ static const char *check_extension(const
>  	return NULL;
>  }
>  
> +/* Transform an incldue path to relative, so that we get more hits */
> +static char *relative(char *path)
> +{
> +	static char result[PATH_MAX];
> +	static char *cwd;
> +	char *proot, *pp;
> +	char *croot, *cp;
> +	char *rp;
> +
> +	/* path is relative */
> +	if (*path != '/')
> +		return path;
> +
> +	rp = x_realpath(path);
> +	if (!rp) {
> +		/* we got two options:
> +		   1) remove the -I.  gcc works with inexistent paths, but this
> +		      will screw up our cache.
> +
> +		   2) Try our best, hoping that path is well formed and won't
> +		      affect us.
> +
> +		   I do #2 for now, in order to keep compiler generality.  Else,
> +		   return NULL.  I prefer #1 though.
> +		*/
> +#if 1
> +		rp = x_strdup(path);
> +#else
> +		return NULL;
> +#endif
> +	}
> +
> +	/* init */
> +	if (!cwd)  {
> +		char *x = gnu_getcwd();
> +
> +		cwd = x_realpath(x);
> +		free(x);
> +	}
> +	result[0] = 0;
> +
> +	/* step 1 - find common root */
> +	cp = croot = cwd;
> +	pp = proot = rp;
> +	while (*pp && *cp) {
> +		if (*pp != *cp)
> +			break;
> +	
> +		if (*pp == '/') {
> +			proot = pp;
> +			croot = cp;
> +		}
> +		pp++; cp++;
> +	}
> +
> +	/* common root is root - don't relativize */
> +	if (croot == cwd) {
> +		free(rp);
> +		return path;
> +	}
> +
> +	/* same dir */	
> +	if (*pp == 0 && *cp == 0) {
> +		strcpy(result, ".");
> +		free(rp);
> +		return result;
> +	}
> +
> +	/* parent */
> +	if (*pp == 0) {
> +		int len = strlen(proot);
> +
> +		if (strncmp(proot, croot, len) == 0 && croot[len] == '/') {
> +			croot++;
> +			proot = NULL;
> +		}
> +	}
> +
> +	/* subdir */
> +	if (*cp == 0) {
> +		int len = strlen(croot);
> +
> +		if (strncmp(croot, proot, len) == 0 && proot[len] == '/') {
> +			croot = cp;
> +			proot += len;
> +		}
> +	}
> +
> +	/* step 2 - cd to common root */
> +	while (*croot) {
> +		if (*croot++ == '/') {
> +			if (strlen(result) + 4 > sizeof(result)) {
> +				cc_log("relative: bad len");
> +				failed();
> +			}
> +			strcat(result, "../");
> +		}
> +	}
> +
> +	/* step 3 - cd to child (if any) */
> +	if (proot) {
> +		proot++;
> +		if (strlen(result) + strlen(proot) + 1 > sizeof(result)) {
> +			cc_log("relative: bad len2");
> +			failed();
> +		}
> +		strcat(result, proot);
> +	}
> +
> +	free(rp);
> +
> +	return result;
> +}
>  
>  /* 
>     process the compiler options to form the correct set of options 
> @@ -704,7 +817,7 @@ static void process_args(int argc, char 
>  
>  		/* options that take an argument */
>  		{
> -			const char *opts[] = {"-I", "-include", "-imacros", "-iprefix",
> +			const char *opts[] = {"-include", "-imacros", "-iprefix",
>  					      "-iwithprefix", "-iwithprefixbefore",
>  					      "-L", "-D", "-U", "-x", "-MF", 
>  					      "-MT", "-MQ", "-isystem", "-aux-info",
> @@ -730,6 +843,32 @@ static void process_args(int argc, char 
>  			if (opts[j]) continue;
>  		}
>  
> +		/* transform paths to relative so that builds in different trees
> +		 * hit
> +		 */
> +		if (strncmp(argv[i], "-I", 2) == 0) {
> +			char *arg = &argv[i][2];
> +
> +			/* see if arg is not glued */
> +			if (*arg == 0) {
> +				if (i == argc-1) {
> +					cc_log("missing argument to -I\n");
> +					stats_update(STATS_ARGS);
> +					failed();
> +				}
> +				i++;
> +				arg = argv[i];
> +			}
> +
> +			if (getenv("CCACHE_RELATIVE"))
> +				arg = relative(arg);
> +			if (!arg)
> +				continue;
> +			args_add(stripped_args, "-I");
> +			args_add(stripped_args, arg);
> +			continue;
> +		}
> +
>  		/* other options */
>  		if (argv[i][0] == '-') {
>  			args_add(stripped_args, argv[i]);
> _______________________________________________
> ccache mailing list
> ccache at lists.samba.org
> https://lists.samba.org/mailman/listinfo/ccache
> 
> 

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