Merge branch 'tb/sanitize-decomposed-utf-8-pathname'

Teaches git to normalize pathnames read from readdir(3) and all
arguments from the command line into precomposed UTF-8 (assuming
that they come as decomposed UTF-8) to work around issues on Mac OS.

I think there still are other places that need conversion
(e.g. paths that are read from stdin for some commands), but this
should be a good first step in the right direction.

* tb/sanitize-decomposed-utf-8-pathname:
  git on Mac OS and precomposed unicode

2 files changed, 235 insertions, 0 deletions

diff --git a/compat/precompose_utf8.c b/compat/precompose_utf8.c
new file mode 100644
index 0000000..d40d1b3
--- /dev/null
+++ b/compat/precompose_utf8.c
@@ -0,0 +1,190 @@
+/*
+ * Converts filenames from decomposed unicode into precomposed unicode.
+ * Used on MacOS X.
+*/
+
+
+#define PRECOMPOSE_UNICODE_C
+
+#include "cache.h"
+#include "utf8.h"
+#include "precompose_utf8.h"
+
+typedef char *iconv_ibp;
+const static char *repo_encoding = "UTF-8";
+const static char *path_encoding = "UTF-8-MAC";
+
+
+static size_t has_utf8(const char *s, size_t maxlen, size_t *strlen_c)
+{
+	const uint8_t *utf8p = (const uint8_t*) s;
+	size_t strlen_chars = 0;
+	size_t ret = 0;
+
+	if ((!utf8p) || (!*utf8p)) {
+		return 0;
+	}
+
+	while((*utf8p) && maxlen) {
+		if (*utf8p & 0x80)
+			ret++;
+		strlen_chars++;
+		utf8p++;
+		maxlen--;
+	}
+	if (strlen_c)
+		*strlen_c = strlen_chars;
+
+	return ret;
+}
+
+
+void probe_utf8_pathname_composition(char *path, int len)
+{
+	const static char *auml_nfc = "\xc3\xa4";
+	const static char *auml_nfd = "\x61\xcc\x88";
+	int output_fd;
+	if (precomposed_unicode != -1)
+		return; /* We found it defined in the global config, respect it */
+	path[len] = 0;
+	strcpy(path + len, auml_nfc);
+	output_fd = open(path, O_CREAT|O_EXCL|O_RDWR, 0600);
+	if (output_fd >=0) {
+		close(output_fd);
+		path[len] = 0;
+		strcpy(path + len, auml_nfd);
+		/* Indicate to the user, that we can configure it to true */
+		if (0 == access(path, R_OK))
+			git_config_set("core.precomposeunicode", "false");
+			/* To be backward compatible, set precomposed_unicode to 0 */
+		precomposed_unicode = 0;
+		path[len] = 0;
+		strcpy(path + len, auml_nfc);
+		unlink(path);
+	}
+}
+
+
+void precompose_argv(int argc, const char **argv)
+{
+	int i = 0;
+	const char *oldarg;
+	char *newarg;
+	iconv_t ic_precompose;
+
+	if (precomposed_unicode != 1)
+		return;
+
+	ic_precompose = iconv_open(repo_encoding, path_encoding);
+	if (ic_precompose == (iconv_t) -1)
+		return;
+
+	while (i < argc) {
+		size_t namelen;
+		oldarg = argv[i];
+		if (has_utf8(oldarg, (size_t)-1, &namelen)) {
+			newarg = reencode_string_iconv(oldarg, namelen, ic_precompose);
+			if (newarg)
+				argv[i] = newarg;
+		}
+		i++;
+	}
+	iconv_close(ic_precompose);
+}
+
+
+PREC_DIR *precompose_utf8_opendir(const char *dirname)
+{
+	PREC_DIR *prec_dir = xmalloc(sizeof(PREC_DIR));
+	prec_dir->dirent_nfc = xmalloc(sizeof(dirent_prec_psx));
+	prec_dir->dirent_nfc->max_name_len = sizeof(prec_dir->dirent_nfc->d_name);
+
+	prec_dir->dirp = opendir(dirname);
+	if (!prec_dir->dirp) {
+		free(prec_dir->dirent_nfc);
+		free(prec_dir);
+		return NULL;
+	} else {
+		int ret_errno = errno;
+		prec_dir->ic_precompose = iconv_open(repo_encoding, path_encoding);
+		/* if iconv_open() fails, die() in readdir() if needed */
+		errno = ret_errno;
+	}
+
+	return prec_dir;
+}
+
+struct dirent_prec_psx *precompose_utf8_readdir(PREC_DIR *prec_dir)
+{
+	struct dirent *res;
+	res = readdir(prec_dir->dirp);
+	if (res) {
+		size_t namelenz = strlen(res->d_name) + 1; /* \0 */
+		size_t new_maxlen = namelenz;
+
+		int ret_errno = errno;
+
+		if (new_maxlen > prec_dir->dirent_nfc->max_name_len) {
+			size_t new_len = sizeof(dirent_prec_psx) + new_maxlen -
+				sizeof(prec_dir->dirent_nfc->d_name);
+
+			prec_dir->dirent_nfc = xrealloc(prec_dir->dirent_nfc, new_len);
+			prec_dir->dirent_nfc->max_name_len = new_maxlen;
+		}
+
+		prec_dir->dirent_nfc->d_ino  = res->d_ino;
+		prec_dir->dirent_nfc->d_type = res->d_type;
+
+		if ((precomposed_unicode == 1) && has_utf8(res->d_name, (size_t)-1, NULL)) {
+			if (prec_dir->ic_precompose == (iconv_t)-1) {
+				die("iconv_open(%s,%s) failed, but needed:\n"
+						"    precomposed unicode is not supported.\n"
+						"    If you wnat to use decomposed unicode, run\n"
+						"    \"git config core.precomposeunicode false\"\n",
+						repo_encoding, path_encoding);
+			} else {
+				iconv_ibp	cp = (iconv_ibp)res->d_name;
+				size_t inleft = namelenz;
+				char *outpos = &prec_dir->dirent_nfc->d_name[0];
+				size_t outsz = prec_dir->dirent_nfc->max_name_len;
+				size_t cnt;
+				errno = 0;
+				cnt = iconv(prec_dir->ic_precompose, &cp, &inleft, &outpos, &outsz);
+				if (errno || inleft) {
+					/*
+					 * iconv() failed and errno could be E2BIG, EILSEQ, EINVAL, EBADF
+					 * MacOS X avoids illegal byte sequemces.
+					 * If they occur on a mounted drive (e.g. NFS) it is not worth to
+					 * die() for that, but rather let the user see the original name
+					*/
+					namelenz = 0; /* trigger strlcpy */
+				}
+			}
+		}
+		else
+			namelenz = 0;
+
+		if (!namelenz)
+			strlcpy(prec_dir->dirent_nfc->d_name, res->d_name,
+							prec_dir->dirent_nfc->max_name_len);
+
+		errno = ret_errno;
+		return prec_dir->dirent_nfc;
+	}
+	return NULL;
+}
+
+
+int precompose_utf8_closedir(PREC_DIR *prec_dir)
+{
+	int ret_value;
+	int ret_errno;
+	ret_value = closedir(prec_dir->dirp);
+	ret_errno = errno;
+	if (prec_dir->ic_precompose != (iconv_t)-1)
+		iconv_close(prec_dir->ic_precompose);
+	free(prec_dir->dirent_nfc);
+	free(prec_dir);
+	errno = ret_errno;
+	return ret_value;
+}
diff --git a/compat/precompose_utf8.h b/compat/precompose_utf8.h
new file mode 100644
index 0000000..3b73585
--- /dev/null
+++ b/compat/precompose_utf8.h
@@ -0,0 +1,45 @@
+#ifndef PRECOMPOSE_UNICODE_H
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <iconv.h>
+
+
+typedef struct dirent_prec_psx {
+	ino_t d_ino;            /* Posix */
+	size_t max_name_len;    /* See below */
+	unsigned char d_type;   /* available on all systems git runs on */
+
+	/*
+	 * See http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/dirent.h.html
+	 * NAME_MAX + 1 should be enough, but some systems have
+	 * NAME_MAX=255 and strlen(d_name) may return 508 or 510
+	 * Solution: allocate more when needed, see precompose_utf8_readdir()
+	 */
+	char   d_name[NAME_MAX+1];
+} dirent_prec_psx;
+
+
+typedef struct {
+	iconv_t ic_precompose;
+	DIR *dirp;
+	struct dirent_prec_psx *dirent_nfc;
+} PREC_DIR;
+
+void precompose_argv(int argc, const char **argv);
+void probe_utf8_pathname_composition(char *, int);
+
+PREC_DIR *precompose_utf8_opendir(const char *dirname);
+struct dirent_prec_psx *precompose_utf8_readdir(PREC_DIR *dirp);
+int precompose_utf8_closedir(PREC_DIR *dirp);
+
+#ifndef PRECOMPOSE_UNICODE_C
+#define dirent dirent_prec_psx
+#define opendir(n) precompose_utf8_opendir(n)
+#define readdir(d) precompose_utf8_readdir(d)
+#define closedir(d) precompose_utf8_closedir(d)
+#define DIR PREC_DIR
+#endif /* PRECOMPOSE_UNICODE_C */
+
+#define  PRECOMPOSE_UNICODE_H
+#endif /* PRECOMPOSE_UNICODE_H */