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[PATCH 1/6] Move computation of absolute paths from Makefile to runtime and compute prefix on the fly if RUNTIME_PREFIX set

From
Steffen Prohaska <prohaska@zib.de>
Date
Jan 10, 2009, 13:50 UTC
Message-ID
<1231595452-27698-1-git-send-email-prohaska@zib.de>

This is the first commit of a series that adds support for relocatable binaries (called RUNTIME_PREFIX). Such binaries can be moved together with the system configuration files to a different directory, as long as the relative paths from the binary to the configuration files is preserved. This functionality is essential on Windows where we deliver git binaries with an installer that allows to freely choose the installation location. The commit series implements RUNTIME_PREFIX only on Windows. Adding support on Unix should not be too hard, though.

This first commits makes all paths relative in the Makefile and teaches system_path() to add the prefix instead. We used to compute absolute paths in the Makefile and passed them to C as defines. We now pass relative paths to C and call system_path() to add the prefix at runtime.

If RUNTIME_PREFIX is unset we use the static prefix. This will be the default on Unix. Thus, the behavior on Unix will stay identical to the old implementation, which added the prefix in the Makefile.

If RUNTIME_PREFIX is set the prefix is computed from the location of the executable. In this case, system_path() tries to strip known directories that executables can be located in from the path of the executable. If the path is successfully stripped it is used as the prefix. For example, if the executable is "/msysgit/bin/git" and BINDIR is "bin", then the prefix computed is "/msysgit".

If the runtime prefix computation fails, we fall back to the static prefix specified in the makefile. This can be the case if the executable is not installed at a known location. Note that our test system sets GIT_CONFIG_NOSYSTEM to tell git to ignore global configuration files during testing. Hence testing does not trigger the fall back.

Note that the implementation requires argv0_path to be set to an absolute path, which is currently the case only on Windows. argv0_path must point to the directory of the executable. We use assert() to verify this in debug builds. On Windows, the wrapper for main() (see compat/mingw.h) guarantees that argv0_path is correctly initialized. On Unix, further work is required before RUNTIME_PREFIX can be enabled.

Signed-off-by: Steffen Prohaska <prohaska@zib.de>
---
 Makefile       |   45 +++++++++++++++++++++++++++++----------------
 builtin-help.c |    4 ++--
 exec_cmd.c     |   54 ++++++++++++++++++++++++++++++++++++++++++++++++++----
 3 files changed, 81 insertions(+), 22 deletions(-)
diff --git a/Makefile b/Makefile
index dee97c1..a7728a3 100644
--- a/Makefile
+++ b/Makefile
@@ -179,28 +179,32 @@ STRIP ?= strip
 # Among the variables below, these:
 #   gitexecdir
 #   template_dir
+#   mandir
+#   infodir
 #   htmldir
 #   ETC_GITCONFIG (but not sysconfdir)
-# can be specified as a relative path ../some/where/else (which must begin
-# with ../); this is interpreted as relative to $(bindir) and "git" at
+# can be specified as a relative path some/where/else;
+# this is interpreted as relative to $(prefix) and "git" at
 # runtime figures out where they are based on the path to the executable.
 # This can help installing the suite in a relocatable way.
 
 prefix = $(HOME)
-bindir = $(prefix)/bin
-mandir = $(prefix)/share/man
-infodir = $(prefix)/share/info
-gitexecdir = $(prefix)/libexec/git-core
+bindir_relative = bin
+bindir = $(prefix)/$(bindir_relative)
+mandir = share/man
+infodir = share/info
+gitexecdir = libexec/git-core
 sharedir = $(prefix)/share
-template_dir = $(sharedir)/git-core/templates
-htmldir=$(sharedir)/doc/git-doc
+template_dir = share/git-core/templates
+htmldir = share/doc/git-doc
 ifeq ($(prefix),/usr)
 sysconfdir = /etc
+ETC_GITCONFIG = $(sysconfdir)/gitconfig
 else
 sysconfdir = $(prefix)/etc
+ETC_GITCONFIG = etc/gitconfig
 endif
 lib = lib
-ETC_GITCONFIG = $(sysconfdir)/gitconfig
 # DESTDIR=
 
 # default configuration for gitweb
@@ -1027,6 +1031,9 @@ ifdef INTERNAL_QSORT
 	COMPAT_CFLAGS += -DINTERNAL_QSORT
 	COMPAT_OBJS += compat/qsort.o
 endif
+ifdef RUNTIME_PREFIX
+	COMPAT_CFLAGS += -DRUNTIME_PREFIX
+endif
 
 ifdef NO_PTHREADS
 	THREADED_DELTA_SEARCH =
@@ -1086,6 +1093,7 @@ ETC_GITCONFIG_SQ = $(subst ','\'',$(ETC_GITCONFIG))
 
 DESTDIR_SQ = $(subst ','\'',$(DESTDIR))
 bindir_SQ = $(subst ','\'',$(bindir))
+bindir_relative_SQ = $(subst ','\'',$(bindir_relative))
 mandir_SQ = $(subst ','\'',$(mandir))
 infodir_SQ = $(subst ','\'',$(infodir))
 gitexecdir_SQ = $(subst ','\'',$(gitexecdir))
@@ -1251,7 +1259,12 @@ git.o git.spec \
 	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) $<
 
 exec_cmd.o: exec_cmd.c GIT-CFLAGS
-	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) '-DGIT_EXEC_PATH="$(gitexecdir_SQ)"' $<
+	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) \
+		'-DGIT_EXEC_PATH="$(gitexecdir_SQ)"' \
+		'-DBINDIR="$(bindir_relative_SQ)"' \
+		'-DPREFIX="$(prefix_SQ)"' \
+		$<
+
 builtin-init-db.o: builtin-init-db.c GIT-CFLAGS
 	$(QUIET_CC)$(CC) -o $*.o -c $(ALL_CFLAGS) -DDEFAULT_GIT_TEMPLATE_DIR='"$(template_dir_SQ)"' $<
 
@@ -1400,17 +1413,17 @@ remove-dashes:
 
 ### Installation rules
 
-ifeq ($(firstword $(subst /, ,$(template_dir))),..)
-template_instdir = $(bindir)/$(template_dir)
-else
+ifeq ($(abspath $(template_dir)),$(template_dir))
 template_instdir = $(template_dir)
+else
+template_instdir = $(prefix)/$(template_dir)
 endif
 export template_instdir
 
-ifeq ($(firstword $(subst /, ,$(gitexecdir))),..)
-gitexec_instdir = $(bindir)/$(gitexecdir)
-else
+ifeq ($(abspath $(gitexecdir)),$(gitexecdir))
 gitexec_instdir = $(gitexecdir)
+else
+gitexec_instdir = $(prefix)/$(gitexecdir)
 endif
 gitexec_instdir_SQ = $(subst ','\'',$(gitexec_instdir))
 export gitexec_instdir
diff --git a/builtin-help.c b/builtin-help.c
index f076efa..9b57a74 100644
--- a/builtin-help.c
+++ b/builtin-help.c
@@ -329,7 +329,7 @@ static void setup_man_path(void)
 	 * old_path, the ':' at the end will let 'man' to try
 	 * system-wide paths after ours to find the manual page. If
 	 * there is old_path, we need ':' as delimiter. */
-	strbuf_addstr(&new_path, GIT_MAN_PATH);
+	strbuf_addstr(&new_path, system_path(GIT_MAN_PATH));
 	strbuf_addch(&new_path, ':');
 	if (old_path)
 		strbuf_addstr(&new_path, old_path);
@@ -375,7 +375,7 @@ static void show_man_page(const char *git_cmd)
 static void show_info_page(const char *git_cmd)
 {
 	const char *page = cmd_to_page(git_cmd);
-	setenv("INFOPATH", GIT_INFO_PATH, 1);
+	setenv("INFOPATH", system_path(GIT_INFO_PATH), 1);
 	execlp("info", "info", "gitman", page, NULL);
 }
 
diff --git a/exec_cmd.c b/exec_cmd.c
index cdd35f9..669b82e 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -9,11 +9,57 @@ static const char *argv0_path;
 
 const char *system_path(const char *path)
 {
-	if (!is_absolute_path(path) && argv0_path) {
-		struct strbuf d = STRBUF_INIT;
-		strbuf_addf(&d, "%s/%s", argv0_path, path);
-		path = strbuf_detach(&d, NULL);
+	static const char *prefix;
+
+	if (is_absolute_path(path)) {
+		return path;
+	}
+
+#ifdef RUNTIME_PREFIX
+	assert(argv0_path);
+	assert(is_absolute_path(argv0_path));
+
+	if (!prefix) {
+		const char *strip[] = {
+			GIT_EXEC_PATH,
+			BINDIR,
+			0
+		};
+		const char **s;
+
+		for (s = strip; *s; s++) {
+			const char *sargv = argv0_path + strlen(argv0_path);
+			const char *ss = *s + strlen(*s);
+			while (argv0_path < sargv && *s < ss
+				&& (*sargv == *ss ||
+				    (is_dir_sep(*sargv) && is_dir_sep(*ss)))) {
+				sargv--;
+				ss--;
+			}
+			if (*s == ss) {
+				struct strbuf d = STRBUF_INIT;
+				/* We also skip the trailing directory separator. */
+				assert(sargv - argv0_path - 1 >= 0);
+				strbuf_add(&d, argv0_path, sargv - argv0_path - 1);
+				prefix = strbuf_detach(&d, NULL);
+				break;
+			}
+		}
 	}
+
+	if (!prefix) {
+		prefix = PREFIX;
+		fprintf(stderr, "RUNTIME_PREFIX requested, "
+				"but prefix computation failed.  "
+				"Using static fallback '%s'.\n", prefix);
+	}
+#else
+	prefix = PREFIX;
+#endif
+
+	struct strbuf d = STRBUF_INIT;
+	strbuf_addf(&d, "%s/%s", prefix, path);
+	path = strbuf_detach(&d, NULL);
 	return path;
 }
 

-- 
1.6.1.85.g32c5d
Next: Steffen Prohaska
Message 1 of 16 in “Move computation of absolute paths from Makefile to runtime and compute prefix on the fly if RUNTIME_PREFIX set”
  1. 1/6 Move computation of absolute paths from Makefile to runtime and compute prefix on the fly if RUNTIME_PREFIX setSteffen Prohaska, Jan 10, 2009
  2. 2/6 Refactor git_set_argv0_path() to git_extract_argv0_path()Steffen Prohaska, Jan 10, 2009
  3. 3/6 Glean libexec path from argv[0] for git-upload-pack and git-receive-pack.Steffen Prohaska, Jan 10, 2009
  4. 4/6 Add calls to git_extract_argv0_path() in programs that call git_config_*Steffen Prohaska, Jan 10, 2009
  5. 5/6 Modify setup_path() to only add git_exec_path() to PATHSteffen Prohaska, Jan 10, 2009
  6. 6/6 Windows: Revert to default paths and convert them by RUNTIME_PREFIXSteffen Prohaska, Jan 10, 2009
  7. Johannes SchindelinJan 10, 2009
  8. Steffen ProhaskaJan 10, 2009
  9. Steffen ProhaskaJan 10, 2009
  10. Junio C HamanoJan 10, 2009
  11. Steffen ProhaskaJan 11, 2009
  12. Junio C HamanoJan 11, 2009
  13. Steffen ProhaskaJan 11, 2009
  14. Johannes SixtJan 13, 2009
  15. Johannes SixtJan 13, 2009
  16. Johannes SixtJan 13, 2009

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