General const correctness fixes

We shouldn't attempt to assign constant strings into char*, as the
string is not writable at runtime.  Likewise we should always be
treating unsigned values as unsigned values, not as signed values.

Most of these are very straightforward.  The only exception is the
(unnecessary) xstrdup/free in builtin-branch.c for the detached
head case.  Since this is a user-level interactive type program
and that particular code path is executed no more than once, I feel
that the extra xstrdup call is well worth the easy elimination of
this warning.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

16 files changed, 40 insertions, 42 deletions

diff --git a/builtin-blame.c b/builtin-blame.c
index 9f7dd4e19f..20966b9e02 100644
--- a/builtin-blame.c
+++ b/builtin-blame.c
@@ -1244,26 +1244,26 @@ static void pass_blame(struct scoreboard *sb, struct origin *origin, int opt)
  */
 struct commit_info
 {
-	char *author;
-	char *author_mail;
+	const char *author;
+	const char *author_mail;
 	unsigned long author_time;
-	char *author_tz;
+	const char *author_tz;
 
 	/* filled only when asked for details */
-	char *committer;
-	char *committer_mail;
+	const char *committer;
+	const char *committer_mail;
 	unsigned long committer_time;
-	char *committer_tz;
+	const char *committer_tz;
 
-	char *summary;
+	const char *summary;
 };
 
 /*
  * Parse author/committer line in the commit object buffer
  */
 static void get_ac_line(const char *inbuf, const char *what,
-			int bufsz, char *person, char **mail,
-			unsigned long *time, char **tz)
+			int bufsz, char *person, const char **mail,
+			unsigned long *time, const char **tz)
 {
 	int len;
 	char *tmp, *endp;
@@ -1280,7 +1280,7 @@ static void get_ac_line(const char *inbuf, const char *what,
 	if (bufsz <= len) {
 	error_out:
 		/* Ugh */
-		person = *mail = *tz = "(unknown)";
+		*mail = *tz = "(unknown)";
 		*time = 0;
 		return;
 	}
diff --git a/builtin-branch.c b/builtin-branch.c
index d371849655..06d8a8ce04 100644
--- a/builtin-branch.c
+++ b/builtin-branch.c
@@ -289,12 +289,13 @@ static void print_ref_list(int kinds, int detached, int verbose, int abbrev)
 	detached = (detached && (kinds & REF_LOCAL_BRANCH));
 	if (detached) {
 		struct ref_item item;
-		item.name = "(no branch)";
+		item.name = xstrdup("(no branch)");
 		item.kind = REF_LOCAL_BRANCH;
 		hashcpy(item.sha1, head_sha1);
 		if (strlen(item.name) > ref_list.maxwidth)
 			      ref_list.maxwidth = strlen(item.name);
 		print_ref_item(&item, ref_list.maxwidth, verbose, abbrev, 1);
+		free(item.name);
 	}
 
 	for (i = 0; i < ref_list.index; i++) {
diff --git a/builtin-for-each-ref.c b/builtin-for-each-ref.c
index b11ca928d6..2b218425aa 100644
--- a/builtin-for-each-ref.c
+++ b/builtin-for-each-ref.c
@@ -301,7 +301,7 @@ static const char *find_wholine(const char *who, int wholen, const char *buf, un
 	return "";
 }
 
-static char *copy_line(const char *buf)
+static const char *copy_line(const char *buf)
 {
 	const char *eol = strchr(buf, '\n');
 	char *line;
@@ -315,7 +315,7 @@ static char *copy_line(const char *buf)
 	return line;
 }
 
-static char *copy_name(const char *buf)
+static const char *copy_name(const char *buf)
 {
 	const char *eol = strchr(buf, '\n');
 	const char *eoname = strstr(buf, " <");
@@ -330,7 +330,7 @@ static char *copy_name(const char *buf)
 	return line;
 }
 
-static char *copy_email(const char *buf)
+static const char *copy_email(const char *buf)
 {
 	const char *email = strchr(buf, '<');
 	const char *eoemail = strchr(email, '>');
diff --git a/builtin-mailinfo.c b/builtin-mailinfo.c
index 766a37ebe2..f54e8752fb 100644
--- a/builtin-mailinfo.c
+++ b/builtin-mailinfo.c
@@ -545,10 +545,10 @@ static int decode_b_segment(char *in, char *ot, char *ep)
 	return 0;
 }
 
-static void convert_to_utf8(char *line, char *charset)
+static void convert_to_utf8(char *line, const char *charset)
 {
-	static char latin_one[] = "latin1";
-	char *input_charset = *charset ? charset : latin_one;
+	static const char latin_one[] = "latin1";
+	const char *input_charset = *charset ? charset : latin_one;
 	char *out = reencode_string(line, metainfo_charset, input_charset);
 
 	if (!out)
diff --git a/builtin-shortlog.c b/builtin-shortlog.c
index 2f71a2a6e2..2d7726e8b9 100644
--- a/builtin-shortlog.c
+++ b/builtin-shortlog.c
@@ -217,13 +217,13 @@ static void get_from_rev(struct rev_info *rev, struct path_list *list)
 
 	prepare_revision_walk(rev);
 	while ((commit = get_revision(rev)) != NULL) {
-		char *author = NULL, *oneline, *buffer;
+		const char *author = NULL, *oneline, *buffer;
 		int authorlen = authorlen, onelinelen;
 
 		/* get author and oneline */
 		for (buffer = commit->buffer; buffer && *buffer != '\0' &&
 				*buffer != '\n'; ) {
-			char *eol = strchr(buffer, '\n');
+			const char *eol = strchr(buffer, '\n');
 
 			if (eol == NULL)
 				eol = buffer + strlen(buffer);
diff --git a/builtin-show-branch.c b/builtin-show-branch.c
index 67ae6bacda..c892f1f7a6 100644
--- a/builtin-show-branch.c
+++ b/builtin-show-branch.c
@@ -721,7 +721,8 @@ int cmd_show_branch(int ac, const char **av, const char *prefix)
 		}
 
 		for (i = 0; i < reflog; i++) {
-			char *logmsg, *msg, *m;
+			char *logmsg, *m;
+			const char *msg;
 			unsigned long timestamp;
 			int tz;
 
diff --git a/cache.h b/cache.h
index c291163e6d..f3d7538aab 100644
--- a/cache.h
+++ b/cache.h
@@ -451,7 +451,7 @@ extern char git_default_email[MAX_GITNAME];
 extern char git_default_name[MAX_GITNAME];
 
 extern char *git_commit_encoding;
-extern char *git_log_output_encoding;
+extern const char *git_log_output_encoding;
 
 extern int copy_fd(int ifd, int ofd);
 extern int read_in_full(int fd, void *buf, size_t count);
diff --git a/commit.c b/commit.c
index 5552527342..5b9234e12e 100644
--- a/commit.c
+++ b/commit.c
@@ -651,7 +651,7 @@ static char *get_header(const struct commit *commit, const char *key)
 	}
 }
 
-static char *replace_encoding_header(char *buf, char *encoding)
+static char *replace_encoding_header(char *buf, const char *encoding)
 {
 	char *encoding_header = strstr(buf, "\nencoding ");
 	char *end_of_encoding_header;
@@ -694,29 +694,26 @@ static char *replace_encoding_header(char *buf, char *encoding)
 }
 
 static char *logmsg_reencode(const struct commit *commit,
-			     char *output_encoding)
+			     const char *output_encoding)
 {
+	static const char *utf8 = "utf-8";
+	const char *use_encoding;
 	char *encoding;
 	char *out;
-	char *utf8 = "utf-8";
 
 	if (!*output_encoding)
 		return NULL;
 	encoding = get_header(commit, "encoding");
-	if (!encoding)
-		encoding = utf8;
-	if (!strcmp(encoding, output_encoding))
+	use_encoding = encoding ? encoding : utf8;
+	if (!strcmp(use_encoding, output_encoding))
 		out = strdup(commit->buffer);
 	else
 		out = reencode_string(commit->buffer,
-				      output_encoding, encoding);
+				      output_encoding, use_encoding);
 	if (out)
 		out = replace_encoding_header(out, output_encoding);
 
-	if (encoding != utf8)
-		free(encoding);
-	if (!out)
-		return NULL;
+	free(encoding);
 	return out;
 }
 
@@ -917,7 +914,7 @@ unsigned long pretty_print_commit(enum cmit_fmt fmt,
 	const char *msg = commit->buffer;
 	int plain_non_ascii = 0;
 	char *reencoded;
-	char *encoding;
+	const char *encoding;
 
 	if (fmt == CMIT_FMT_USERFORMAT)
 		return format_commit_message(commit, msg, buf, space);
diff --git a/convert-objects.c b/convert-objects.c
index b5f41ae2e3..4809f9199f 100644
--- a/convert-objects.c
+++ b/convert-objects.c
@@ -132,7 +132,7 @@ static void convert_tree(void *buffer, unsigned long size, unsigned char *result
 	unsigned long orig_size = size;
 
 	while (size) {
-		int len = 1+strlen(buffer);
+		size_t len = 1+strlen(buffer);
 
 		convert_binary_sha1((char *) buffer + len);
 
diff --git a/environment.c b/environment.c
index 49486dd9f1..0151ad0722 100644
--- a/environment.c
+++ b/environment.c
@@ -21,7 +21,7 @@ int log_all_ref_updates = -1; /* unspecified */
 int warn_ambiguous_refs = 1;
 int repository_format_version;
 char *git_commit_encoding;
-char *git_log_output_encoding;
+const char *git_log_output_encoding;
 int shared_repository = PERM_UMASK;
 const char *apply_default_whitespace;
 int zlib_compression_level = Z_DEFAULT_COMPRESSION;
diff --git a/fast-import.c b/fast-import.c
index cc3347b23d..132dd9c938 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -757,7 +757,7 @@ static char *create_index(void)
 static char *keep_pack(char *curr_index_name)
 {
 	static char name[PATH_MAX];
-	static char *keep_msg = "fast-import";
+	static const char *keep_msg = "fast-import";
 	int keep_fd;
 
 	chmod(pack_data->pack_name, 0444);
diff --git a/index-pack.c b/index-pack.c
index cf81a99500..b405864be9 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -753,7 +753,7 @@ static void final(const char *final_pack_name, const char *curr_pack_name,
 		  const char *keep_name, const char *keep_msg,
 		  unsigned char *sha1)
 {
-	char *report = "pack";
+	const char *report = "pack";
 	char name[PATH_MAX];
 	int err;
 
diff --git a/interpolate.c b/interpolate.c
index f992ef7753..fb30694f47 100644
--- a/interpolate.c
+++ b/interpolate.c
@@ -55,7 +55,7 @@ int interpolate(char *result, int reslen,
 	const char *src = orig;
 	char *dest = result;
 	int newlen = 0;
-	char *name, *value;
+	const char *name, *value;
 	int namelen, valuelen;
 	int i;
 	char c;
diff --git a/interpolate.h b/interpolate.h
index 190a180b58..16a26b9986 100644
--- a/interpolate.h
+++ b/interpolate.h
@@ -12,7 +12,7 @@
  */
 
 struct interp {
-	char *name;
+	const char *name;
 	char *value;
 };
 
diff --git a/path.c b/path.c
index c5d25a4b90..6395cf2309 100644
--- a/path.c
+++ b/path.c
@@ -252,7 +252,7 @@ char *enter_repo(char *path, int strict)
 
 	if (access("objects", X_OK) == 0 && access("refs", X_OK) == 0 &&
 	    validate_headref("HEAD") == 0) {
-		putenv("GIT_DIR=.");
+		setenv("GIT_DIR", ".", 1);
 		check_repository_format();
 		return path;
 	}
diff --git a/sha1_file.c b/sha1_file.c
index cfce7acdbd..b17a828795 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2065,10 +2065,9 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object,
 	     enum object_type type, const char *path)
 {
 	unsigned long size = st->st_size;
-	void *buf;
+	void *buf = NULL;
 	int ret, re_allocated = 0;
 
-	buf = "";
 	if (size)
 		buf = xmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
 	close(fd);