Don't set safe.dir=* in main app

Instead, set it in tests.  This requires a new flag `--add-git-config`
which is like `--git-config` but uses repeated calls to the flag instead
of a comma-separated value.

Author: thockin

Dockerfile.in

@@ -103,7 +103,6 @@ RUN rm -rf \
     /usr/lib/git-core/git-http-push \
     /usr/lib/git-core/git-imap-send \
     /usr/lib/git-core/git-instaweb \
-    /usr/lib/git-core/git-sh-i18n--envsubst \
     /usr/lib/git-core/scalar \
     /usr/lib/openssh/ssh-keysign \
     /usr/lib/openssh/ssh-pkcs11-helper \

README.md

@@ -232,6 +232,26 @@ OPTIONS
     error while a misspelled environment variable is silently ignored.  Some
     options can only be specified as an environment variable.
 
+    --add-git-config <string>
+            Add one git config option.  The parsed key and value are passed to
+            'git config' and must be valid syntax for that command.  This flag
+            can be specified more than once.  This is similar to --git-config,
+            but allows multiple discrete uses of the flag instead of a single
+            comma-separated string.
+
+            Both keys and values can be either quoted or unquoted strings.
+            Within quoted keys and all values (quoted or not), the following
+            escape sequences are supported:
+                '\n' => [newline]
+                '\t' => [tab]
+                '\"' => '"'
+                '\,' => ','
+                '\\' => '\'
+            To include a colon within a key (e.g. a URL) the key must be
+            quoted.  Within unquoted values commas must be escaped.  Within
+            quoted values commas may be escaped, but are not required to be.
+            Any other escape sequence is an error.
+
     --add-user, $GITSYNC_ADD_USER
             Add a record to /etc/passwd for the current UID/GID.  This is
             needed to use SSH with an arbitrary UID.  This assumes that
@@ -312,7 +332,8 @@ OPTIONS
     --git-config <string>, $GITSYNC_GIT_CONFIG
             Additional git config options in a comma-separated 'key:val'
             format.  The parsed keys and values are passed to 'git config' and
-            must be valid syntax for that command.
+            must be valid syntax for that command.  This is similar to
+            --add-git-config, but uses a single comma-separated string.
 
             Both keys and values can be either quoted or unquoted strings.
             Within quoted keys and all values (quoted or not), the following

main.go

@@ -297,9 +297,12 @@ func main() {
 	flGitCmd := pflag.String("git",
 		envString("git", "GITSYNC_GIT", "GIT_SYNC_GIT"),
 		"the git command to run (subject to PATH search, mostly for testing)")
-	flGitConfig := pflag.String("git-config",
+	flGitConfigString := pflag.String("git-config",
 		envString("", "GITSYNC_GIT_CONFIG", "GIT_SYNC_GIT_CONFIG"),
 		"additional git config options in 'section.var1:val1,\"section.sub.var2\":\"val2\"' format")
+	flGitConfigList := pflag.StringArray("add-git-config",
+		nil,
+		"one additional git config option in 'section.var1:val1' format, can be repeated")
 	flGitGC := pflag.String("git-gc",
 		envString("always", "GITSYNC_GIT_GC", "GIT_SYNC_GIT_GC"),
 		"git garbage collection behavior: one of 'auto', 'always', 'aggressive', or 'off'")
@@ -786,9 +789,16 @@ func main() {
 	}
 
 	// This needs to be after all other git-related config flags.
-	if *flGitConfig != "" {
-		if err := git.SetupExtraGitConfigs(ctx, *flGitConfig); err != nil {
-			log.Error(err, "can't set additional git configs", "configs", *flGitConfig)
+	if *flGitConfigString != "" {
+		if err := git.SetupExtraGitConfigs(ctx, *flGitConfigString); err != nil {
+			log.Error(err, "can't set additional git configs", "configs", *flGitConfigString)
+			os.Exit(1)
+		}
+	}
+	if len(*flGitConfigList) > 0 {
+		str := strings.Join(*flGitConfigList, ",")
+		if err := git.SetupExtraGitConfigs(ctx, str); err != nil {
+			log.Error(err, "can't set additional git configs", "configs", str)
 			os.Exit(1)
 		}
 	}
@@ -2164,10 +2174,6 @@ func (git *repoSync) SetupDefaultGitConfigs(ctx context.Context) error {
 		// Never prompt for a password.
 		key: "core.askPass",
 		val: "true",
-	}, {
-		// Mark repos as safe (avoid a "dubious ownership" error).
-		key: "safe.directory",
-		val: "*",
 	}}
 
 	for _, kv := range configs {
@@ -2455,6 +2461,26 @@ OPTIONS
     error while a misspelled environment variable is silently ignored.  Some
     options can only be specified as an environment variable.
 
+    --add-git-config <string>
+            Add one git config option.  The parsed key and value are passed to
+            'git config' and must be valid syntax for that command.  This flag
+            can be specified more than once.  This is similar to --git-config,
+            but allows multiple discrete uses of the flag instead of a single
+            comma-separated string.
+
+            Both keys and values can be either quoted or unquoted strings.
+            Within quoted keys and all values (quoted or not), the following
+            escape sequences are supported:
+                '\n' => [newline]
+                '\t' => [tab]
+                '\"' => '"'
+                '\,' => ','
+                '\\' => '\'
+            To include a colon within a key (e.g. a URL) the key must be
+            quoted.  Within unquoted values commas must be escaped.  Within
+            quoted values commas may be escaped, but are not required to be.
+            Any other escape sequence is an error.
+
     --add-user, $GITSYNC_ADD_USER
             Add a record to /etc/passwd for the current UID/GID.  This is
             needed to use SSH with an arbitrary UID.  This assumes that
@@ -2535,7 +2561,8 @@ OPTIONS
     --git-config <string>, $GITSYNC_GIT_CONFIG
             Additional git config options in a comma-separated 'key:val'
             format.  The parsed keys and values are passed to 'git config' and
-            must be valid syntax for that command.
+            must be valid syntax for that command.  This is similar to
+            --add-git-config, but uses a single comma-separated string.
 
             Both keys and values can be either quoted or unquoted strings.
             Within quoted keys and all values (quoted or not), the following

test_e2e.sh

@@ -368,7 +368,8 @@ function GIT_SYNC() {
             --add-user \
             --group-write \
             --touch-file="$INTERLOCK" \
-            --git-config='protocol.file.allow:always' \
+            --add-git-config='protocol.file.allow:always' \
+            --add-git-config='safe.directory:*' \
             --http-bind=":$HTTP_PORT" \
             --http-metrics \
             --http-pprof \
@@ -3441,7 +3442,10 @@ function e2e::additional_git_configs() {
         --repo="file://$REPO" \
         --root="$ROOT" \
         --link="link" \
-        --git-config='http.postBuffer:10485760,sect.k1:"a val",sect.k2:another val'
+        --git-config='http.postBuffer:10485760,sect.k1:"a val",sect.k2:another val' \
+        --add-git-config='sect.k3:a val' \
+        --add-git-config='sect.k4:"a val with quotes"' \
+        --add-git-config='"sect.k5":"quoted_all"'
     assert_link_exists "$ROOT/link"
     assert_file_exists "$ROOT/link/file"
     assert_file_eq "$ROOT/link/file" "${FUNCNAME[0]}"