ccache.c

ccache 是一个快速的编译器缓存。当您编译一个程序的时候

	}

	/* get rid of the intermediate preprocessor file */
	if (i_tmpfile) {
		if (!direct_i_file) {
			unlink(i_tmpfile);
		}
		free(i_tmpfile);
		i_tmpfile = NULL;
	}

	/* send the cpp stderr, if applicable */
	fd_cpp_stderr = open(cpp_stderr, O_RDONLY);
	if (fd_cpp_stderr != -1) {
		copy_fd(fd_cpp_stderr, 2);
		close(fd_cpp_stderr);
		unlink(cpp_stderr);
		free(cpp_stderr);
		cpp_stderr = NULL;
	}

	/* send the stderr */
	copy_fd(fd_stderr, 2);
	close(fd_stderr);

	/* and exit with the right status code */
	if (first) {
		cc_log("got cached result for %s\n", output_file);
		stats_update(STATS_CACHED);
	}

	exit(0);
}

/* find the real compiler. We just search the PATH to find a executable of the 
   same name that isn't a link to ourselves */
static void find_compiler(int argc, char **argv)
{
	char *base;
	char *path;

	orig_args = args_init(argc, argv);

	base = str_basename(argv[0]);

	/* we might be being invoked like "ccache gcc -c foo.c" */
	if (strcmp(base, MYNAME) == 0) {
		args_remove_first(orig_args);
		free(base);
		if (strchr(argv[1],'/')) {
			/* a full path was given */
			return;
		}
		base = str_basename(argv[1]);
	}

	/* support user override of the compiler */
	if ((path=getenv("CCACHE_CC"))) {
		base = strdup(path);
	}

	orig_args->argv[0] = find_executable(base, MYNAME);

	/* can't find the compiler! */
	if (!orig_args->argv[0]) {
		stats_update(STATS_COMPILER);
		perror(base);
		exit(1);
	}
}


/* check a filename for C/C++ extension. Return the pre-processor
   extension */
static const char *check_extension(const char *fname, int *direct_i)
{
	int i;
	const char *p;

	if (direct_i) {
		*direct_i = 0;
	}

	p = strrchr(fname, '.');
	if (!p) return NULL;
	p++;
	for (i=0; extensions[i].extension; i++) {
		if (strcmp(p, extensions[i].extension) == 0) {
			if (direct_i && strcmp(p, extensions[i].i_extension) == 0) {
				*direct_i = 1;
			}
			p = getenv("CCACHE_EXTENSION");
			if (p) return p;
			return extensions[i].i_extension;
		}
	}
	return NULL;
}


/* 
   process the compiler options to form the correct set of options 
   for obtaining the preprocessor output
*/
static void process_args(int argc, char **argv)
{
	int i;
	int found_c_opt = 0;
	int found_S_opt = 0;
	struct stat st;
	char *e;

	stripped_args = args_init(0, NULL);

	args_add(stripped_args, argv[0]);

	for (i=1; i<argc; i++) {
		/* some options will never work ... */
		if (strcmp(argv[i], "-E") == 0) {
			failed();
		}

		/* these are too hard */
		if (strcmp(argv[i], "-fbranch-probabilities")==0 ||
		    strcmp(argv[i], "-M") == 0 ||
		    strcmp(argv[i], "-MM") == 0 ||
		    strcmp(argv[i], "-x") == 0) {
			cc_log("argument %s is unsupported\n", argv[i]);
			stats_update(STATS_UNSUPPORTED);
			failed();
			continue;
		}

		/* we must have -c */
		if (strcmp(argv[i], "-c") == 0) {
			args_add(stripped_args, argv[i]);
			found_c_opt = 1;
			continue;
		}

		/* -S changes the default extension */
		if (strcmp(argv[i], "-S") == 0) {
			args_add(stripped_args, argv[i]);
			found_S_opt = 1;
			continue;
		}
		
		/* we need to work out where the output was meant to go */
		if (strcmp(argv[i], "-o") == 0) {
			if (i == argc-1) {
				cc_log("missing argument to %s\n", argv[i]);
				stats_update(STATS_ARGS);
				failed();
			}
			output_file = argv[i+1];
			i++;
			continue;
		}
		
		/* alternate form of -o, with no space */
		if (strncmp(argv[i], "-o", 2) == 0) {
			output_file = &argv[i][2];
			continue;
		}

		/* debugging is handled specially, so that we know if we
		   can strip line number info 
		*/
		if (strncmp(argv[i], "-g", 2) == 0) {
			args_add(stripped_args, argv[i]);
			if (strcmp(argv[i], "-g0") != 0) {
				enable_unify = 0;
			}
			continue;
		}

		/* The user knows best: just swallow the next arg */
		if (strcmp(argv[i], "--ccache-skip") == 0) {
			i++;
			if (i == argc) {
				failed();
			}
			args_add(stripped_args, argv[i]);
			continue;
		}

		/* options that take an argument */
		{
			const char *opts[] = {"-I", "-include", "-imacros", "-iprefix",
					      "-iwithprefix", "-iwithprefixbefore",
					      "-L", "-D", "-U", "-x", "-MF", 
					      "-MT", "-MQ", "-isystem", "-aux-info",
					      "--param", "-A", "-Xlinker", "-u",
					      "-idirafter", 
					      NULL};
			int j;
			for (j=0;opts[j];j++) {
				if (strcmp(argv[i], opts[j]) == 0) {
					if (i == argc-1) {
						cc_log("missing argument to %s\n", 
						       argv[i]);
						stats_update(STATS_ARGS);
						failed();
					}
						
					args_add(stripped_args, argv[i]);
					args_add(stripped_args, argv[i+1]);
					i++;
					break;
				}
			}
			if (opts[j]) continue;
		}

		/* other options */
		if (argv[i][0] == '-') {
			args_add(stripped_args, argv[i]);
			continue;
		}

		/* if an argument isn't a plain file then assume its
		   an option, not an input file. This allows us to
		   cope better with unusual compiler options */
		if (stat(argv[i], &st) != 0 || !S_ISREG(st.st_mode)) {
			args_add(stripped_args, argv[i]);
			continue;			
		}

		if (input_file) {
			if (check_extension(argv[i], NULL)) {
				cc_log("multiple input files (%s and %s)\n",
				       input_file, argv[i]);
				stats_update(STATS_MULTIPLE);
			} else if (!found_c_opt) {
				cc_log("called for link with %s\n", argv[i]);
				if (strstr(argv[i], "conftest.")) {
					stats_update(STATS_CONFTEST);
				} else {
					stats_update(STATS_LINK);
				}
			} else {
				cc_log("non C/C++ file %s\n", argv[i]);
				stats_update(STATS_NOTC);
			}
			failed();
		}

		input_file = argv[i];
	}

	if (!input_file) {
		cc_log("No input file found\n");
		stats_update(STATS_NOINPUT);
		failed();
	}

	i_extension = check_extension(input_file, &direct_i_file);
	if (i_extension == NULL) {
		cc_log("Not a C/C++ file - %s\n", input_file);
		stats_update(STATS_NOTC);
		failed();
	}

	if (!found_c_opt) {
		cc_log("No -c option found for %s\n", input_file);
		/* I find that having a separate statistic for autoconf tests is useful,
		   as they are the dominant form of "called for link" in many cases */
		if (strstr(input_file, "conftest.")) {
			stats_update(STATS_CONFTEST);
		} else {
			stats_update(STATS_LINK);
		}
		failed();
	}


	/* don't try to second guess the compilers heuristics for stdout handling */
	if (output_file && strcmp(output_file, "-") == 0) {
		stats_update(STATS_OUTSTDOUT);
		failed();
	}

	if (!output_file) {
		char *p;
		output_file = x_strdup(input_file);
		if ((p = strrchr(output_file, '/'))) {
			output_file = p+1;
		}
		p = strrchr(output_file, '.');
		if (!p || !p[1]) {
			cc_log("badly formed output_file %s\n", output_file);
			stats_update(STATS_ARGS);
			failed();
		}
		p[1] = found_S_opt ? 's' : 'o';
		p[2] = 0;
	}

	/* cope with -o /dev/null */
	if (strcmp(output_file,"/dev/null") != 0 && stat(output_file, &st) == 0 && !S_ISREG(st.st_mode)) {
		cc_log("Not a regular file %s\n", output_file);
		stats_update(STATS_DEVICE);
		failed();
	}

	if ((e=getenv("CCACHE_PREFIX"))) {
		char *p = find_executable(e, MYNAME);
		if (!p) {
			perror(e);
			exit(1);
		}
		args_add_prefix(stripped_args, p);
	}
}

/* the main ccache driver function */
static void ccache(int argc, char *argv[])
{
	/* find the real compiler */
	find_compiler(argc, argv);
	
	/* we might be disabled */
	if (getenv("CCACHE_DISABLE")) {
		cc_log("ccache is disabled\n");
		failed();
	}

	if (getenv("CCACHE_UNIFY")) {
		enable_unify = 1;
	}

	/* process argument list, returning a new set of arguments for pre-processing */
	process_args(orig_args->argc, orig_args->argv);

	/* run with -E to find the hash */
	find_hash(stripped_args);

	/* if we can return from cache at this point then do */
	from_cache(1);
	
	/* run real compiler, sending output to cache */
	to_cache(stripped_args);

	/* return from cache */
	from_cache(0);

	/* oh oh! */
	cc_log("secondary from_cache failed!\n");
	stats_update(STATS_ERROR);
	failed();
}


static void usage(void)
{
	printf("ccache, a compiler cache. Version %s\n", CCACHE_VERSION);
	printf("Copyright Andrew Tridgell, 2002\n\n");
	
	printf("Usage:\n");
	printf("\tccache [options]\n");
	printf("\tccache compiler [compile options]\n");
	printf("\tcompiler [compile options]    (via symbolic link)\n");
	printf("\nOptions:\n");

	printf("-s                      show statistics summary\n");
	printf("-z                      zero statistics\n");
	printf("-c                      run a cache cleanup\n");
	printf("-C                      clear the cache completely\n");
	printf("-F <maxfiles>           set maximum files in cache\n");
	printf("-M <maxsize>            set maximum size of cache (use G, M or K)\n");
	printf("-h                      this help page\n");
	printf("-V                      print version number\n");
}

/* the main program when not doing a compile */
static int ccache_main(int argc, char *argv[])
{
	extern int optind;
	int c;
	size_t v;

	while ((c = getopt(argc, argv, "hszcCF:M:V")) != -1) {
		switch (c) {
		case 'V':
			printf("ccache version %s\n", CCACHE_VERSION);
			printf("Copyright Andrew Tridgell 2002\n");
			printf("Released under the GNU GPL v2 or later\n");
			exit(0);

		case 'h':
			usage();
			exit(0);
			
		case 's':
			stats_summary();
			break;

		case 'c':
			cleanup_all(cache_dir);
			printf("Cleaned cache\n");
			break;

		case 'C':
			wipe_all(cache_dir);
			printf("Cleared cache\n");
			break;

		case 'z':
			stats_zero();
			printf("Statistics cleared\n");
			break;

		case 'F':
			v = atoi(optarg);
			stats_set_limits(v, -1);
			printf("Set cache file limit to %u\n", (unsigned)v);
			break;

		case 'M':
			v = value_units(optarg);
			stats_set_limits(-1, v);
			printf("Set cache size limit to %uk\n", (unsigned)v);
			break;

		default:
			usage();
			exit(1);
		}
	}

	return 0;
}


/* Make a copy of stderr that will not be cached, so things like
   distcc can send networking errors to it. */
static void setup_uncached_err(void)
{
	char *buf;
	int uncached_fd;
	
	uncached_fd = dup(2);
	if (uncached_fd == -1) {
		cc_log("dup(2) failed\n");
		failed();
	}

	/* leak a pointer to the environment */
	x_asprintf(&buf, "UNCACHED_ERR_FD=%d", uncached_fd);

	if (putenv(buf) == -1) {
		cc_log("putenv failed\n");
		failed();
	}
}


int main(int argc, char *argv[])
{
	char *p;

	cache_dir = getenv("CCACHE_DIR");
	if (!cache_dir) {
		x_asprintf(&cache_dir, "%s/.ccache", getenv("HOME"));
	}

	cache_logfile = getenv("CCACHE_LOGFILE");

	setup_uncached_err();
	

	/* the user might have set CCACHE_UMASK */
	p = getenv("CCACHE_UMASK");
	if (p) {
		mode_t mask;
		errno = 0;
		mask = strtol(p, NULL, 8);
		if (errno == 0) {
			umask(mask);
		}
	}


	/* check if we are being invoked as "ccache" */
	if (strlen(argv[0]) >= strlen(MYNAME) &&
	    strcmp(argv[0] + strlen(argv[0]) - strlen(MYNAME), MYNAME) == 0) {
		if (argc < 2) {
			usage();
			exit(1);
		}
		/* if the first argument isn't an option, then assume we are
		   being passed a compiler name and options */
		if (argv[1][0] == '-') {
			return ccache_main(argc, argv);
		}
	}

	/* make sure the cache dir exists */
	if (create_dir(cache_dir) != 0) {
		fprintf(stderr,"ccache: failed to create %s (%s)\n", 
			cache_dir, strerror(errno));
		exit(1);
	}

	ccache(argc, argv);
	return 1;
}