In https://lore.kernel.org/git/xmqqv99i4ck2.fsf@gitster.g/ Junio and Christian talked about the problem of using strbuf_replace() to replace $ARG: 1. if the user's script has more than one $ARG, only the first one will be replaced, which is incorrected. 2. $ARG is textually replaced without shell syntax, which may result a broken command when $ARG include some unmatching single quote, very unsafe. Now pass trailer value as $1 to the trailer command with another trailer.<token>.cmd config, to solve these above two problems, We are now writing documents that are more readable and correct than before. ZheNing Hu (2): [GSOC] docs: correct descript of trailer.<token>.command [GSOC] trailer: add new .cmd config option Documentation/git-interpret-trailers.txt | 96 ++++++++++++++++++++---- t/t7513-interpret-trailers.sh | 84 +++++++++++++++++++++ trailer.c | 37 ++++++--- 3 files changed, 190 insertions(+), 27 deletions(-) base-commit: 142430338477d9d1bb25be66267225fb58498d92 Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-913%2Fadlternative%2Ftrailer-pass-ARG-env-v9 Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-913/adlternative/trailer-pass-ARG-env-v9 Pull-Request: https://github.com/gitgitgadget/git/pull/913 Range-diff vs v8: 1: 505903811df8 ! 1: 8129ef6c476b [GSOC] docs: correct descript of trailer.<token>.command @@ Commit message it to increase its readability. In addition, clarify that `$ARG` in command can only be - replaced once since `$ARG` is text replacement. + replaced once. Signed-off-by: ZheNing Hu <adlternative@xxxxxxxxx> ## Documentation/git-interpret-trailers.txt ## -@@ Documentation/git-interpret-trailers.txt: trailer.<token>.command:: - specified <token>. +@@ Documentation/git-interpret-trailers.txt: trailer.<token>.ifmissing:: + that option for trailers with the specified <token>. + + trailer.<token>.command:: +- This option can be used to specify a shell command that will +- be called to automatically add or modify a trailer with the +- specified <token>. ++ This option can be used to specify a shell command that will be called: ++ once to automatically add a trailer with the specified <token>, and then ++ each time a '--trailer <token>=<value>' argument to modify the <value> of ++ the trailer that this option would produce. + - When this option is specified, the behavior is as if a special +-When this option is specified, the behavior is as if a special -'<token>=<value>' argument were added at the beginning of the command -line, where <value> is taken to be the standard output of the -specified command with any leading and trailing whitespace trimmed -off. -+'--trailer <token>=<value>' argument was added at the beginning of -+the "git interpret-trailers" command, where <value> is taken to be the -+standard output of the specified command with any leading and trailing -+whitespace trimmed off. ++When the specified command is first called to add a trailer ++with the specified <token>, the behavior is as if a special ++'--trailer <token>=<value>' argument was added at the beginning ++of the "git interpret-trailers" command, where <value> ++is taken to be the standard output of the command with any ++leading and trailing whitespace trimmed off. + -If the command contains the `$ARG` string, this string will be -replaced with the <value> part of an existing trailer with the same -<token>, if any, before the command is launched. -+The first occurrence of substring `$ARG` will be replaced with the -+<value> part of an existing trailer with the same <token>, if any, -+before the command is launched. ++If some '--trailer <token>=<value>' arguments are also passed ++on the command line, the command is called again once for each ++of these arguments with the same <token>. And the <value> part ++of these arguments, if any, will be used to replace the first ++occurrence of substring `$ARG` in the command. This way the ++command can produce a <value> computed from the <value> passed ++in the '--trailer <token>=<value>' argument. + - If some '<token>=<value>' arguments are also passed on the command +-If some '<token>=<value>' arguments are also passed on the command -line, when a 'trailer.<token>.command' is configured, the command will -also be executed for each of these arguments. And the <value> part of -these arguments, if any, will be used to replace the `$ARG` string in -the command. -+line, when a 'trailer.<token>.command' is configured, the command is run -+once for each these arguments with the same <token>. And the <value> -+part of these arguments, if any, will be used to replace the first `$ARG` -+string in the command. ++For consistency, the first occurrence of substring `$ARG` is ++also replaced, this time with the empty string, in the command ++when the command is first called to add a trailer with the ++specified <token>. EXAMPLES -------- 2: 3dc8983a4702 ! 2: 7f645ec95f48 [GSOC] trailer: add new .cmd config option @@ Commit message The `trailer.<token>.command` configuration variable specifies a command (run via the shell, so it does not have - to be a single name of or path to the command, but can be a + to be a single name or path to the command, but can be a shell script), and the first occurrence of substring $ARG is replaced with the value given to the `interpret-trailer` - command for the token. This has two downsides: + command for the token in a '--trailer <token>=<value>' argument. + + This has two downsides: * The use of $ARG in the mechanism misleads the users that the value is passed in the shell variable, and tempt them @@ Commit message Signed-off-by: ZheNing Hu <adlternative@xxxxxxxxx> ## Documentation/git-interpret-trailers.txt ## -@@ Documentation/git-interpret-trailers.txt: trailer.<token>.command:: - be called to automatically add or modify a trailer with the - specified <token>. - + --When this option is specified, the behavior is as if a special --'--trailer <token>=<value>' argument was added at the beginning of --the "git interpret-trailers" command, where <value> is taken to be the --standard output of the specified command with any leading and trailing --whitespace trimmed off. -+When this option is specified, the first occurrence of substring $ARG is -+replaced with the value given to the `interpret-trailer` command for the -+same token. It passes the value through `$ARG`, otherwise this option behaves -+in the same way as 'trailer.<token>.cmd'. +@@ Documentation/git-interpret-trailers.txt: trailer.<token>.ifmissing:: + that option for trailers with the specified <token>. + + trailer.<token>.command:: ++ This option behaves in the same way as 'trailer.<token>.cmd', except ++ that it doesn't pass anything as argument to the specified command. ++ Instead the first occurrence of substring $ARG is replaced by the ++ value that would be passed as argument. +++ ++The 'trailer.<token>.command' option has been deprecated in favor of ++'trailer.<token>.cmd' due to the fact that $ARG in the user's command is ++only replaced once and that the original way of replacing $ARG is not safe. ++ -+The 'trailer.<token>.command' option has been deprecated due to the fact -+that $ARG in the user's command can only be replaced once and that the -+original way of replacing $ARG was not safe. Now the preferred option is -+'trailer.<token>.cmd', which uses a positional argument to pass the value. - + --The first occurrence of substring `$ARG` will be replaced with the --<value> part of an existing trailer with the same <token>, if any, --before the command is launched. +When both 'trailer.<token>.cmd' and 'trailer.<token>.command' are given +for the same <token>, 'trailer.<token>.cmd' is used and +'trailer.<token>.command' is ignored. + +trailer.<token>.cmd:: -+ The command specified by this configuration variable is run -+ with a single argument, which is the <value> part of a -+ `--trailer <token>=<value>` on the command line. The output -+ from the command is then used as the value for the <token> -+ in the resulting trailer. -++ -+When this option is specified, the behavior is as if a -+'--trailer <token>=<value>' argument was added at the beginning of -+the "git interpret-trailers" command, the command specified by this -+configuration variable will be called with an empty string as the -+argument. + This option can be used to specify a shell command that will be called: + once to automatically add a trailer with the specified <token>, and then + each time a '--trailer <token>=<value>' argument to modify the <value> of +@@ Documentation/git-interpret-trailers.txt: leading and trailing whitespace trimmed off. + If some '--trailer <token>=<value>' arguments are also passed + on the command line, the command is called again once for each + of these arguments with the same <token>. And the <value> part +-of these arguments, if any, will be used to replace the first +-occurrence of substring `$ARG` in the command. This way the +-command can produce a <value> computed from the <value> passed +-in the '--trailer <token>=<value>' argument. ++of these arguments, if any, will be passed to the command as its ++first argument. This way the command can produce a <value> computed ++from the <value> passed in the '--trailer <token>=<value>' argument. + --If some '<token>=<value>' arguments are also passed on the command --line, when a 'trailer.<token>.command' is configured, the command is run --once for each these arguments with the same <token>. And the <value> --part of these arguments, if any, will be used to replace the first `$ARG` --string in the command. -+If some '--trailer <token>=<value>' arguments are also passed on the -+command line, when a 'trailer.<token>.cmd' is configured, the command -+is run once for each `--trailer <token>=<value>` on the command line -+with the same <token>. And the <value> part of these arguments, if any, -+will be passed to the command as its first argument. +-For consistency, the first occurrence of substring `$ARG` is +-also replaced, this time with the empty string, in the command +-when the command is first called to add a trailer with the +-specified <token>. ++For consistency, the $1 is also passed, this time with the empty string, ++in the command when the command is first called to add a trailer with ++the specified <token>. EXAMPLES -------- -- gitgitgadget
