config: allow specifying config entries via envvar pairs

While we currently have the `GIT_CONFIG_PARAMETERS` environment variable
which can be used to pass runtime configuration data to git processes,
it's an internal implementation detail and not supposed to be used by
end users.

Next to being for internal use only, this way of passing config entries
has a major downside: the config keys need to be parsed as they contain
both key and value in a single variable. As such, it is left to the user
to escape any potentially harmful characters in the value, which is
quite hard to do if values are controlled by a third party.

This commit thus adds a new way of adding config entries via the
environment which gets rid of this shortcoming. If the user passes the
`GIT_CONFIG_COUNT=$n` environment variable, Git will parse environment
variable pairs `GIT_CONFIG_KEY_$i` and `GIT_CONFIG_VALUE_$i` for each
`i` in `[0,n)`.

While the same can be achieved with `git -c <name>=<value>`, one may
wish to not do so for potentially sensitive information. E.g. if one
wants to set `http.extraHeader` to contain an authentication token,
doing so via `-c` would trivially leak those credentials via e.g. ps(1),
which typically also shows command arguments.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Patrick Steinhardt 2021-01-12 13:27:14 +01:00 committed by Junio C Hamano
parent b9d147fb15
commit d8d77153ea
5 changed files with 191 additions and 9 deletions

View File

@ -337,6 +337,22 @@ GIT_CONFIG_NOSYSTEM::
See also <<FILES>>.
GIT_CONFIG_COUNT::
GIT_CONFIG_KEY_<n>::
GIT_CONFIG_VALUE_<n>::
If GIT_CONFIG_COUNT is set to a positive number, all environment pairs
GIT_CONFIG_KEY_<n> and GIT_CONFIG_VALUE_<n> up to that number will be
added to the process's runtime configuration. The config pairs are
zero-indexed. Any missing key or value is treated as an error. An empty
GIT_CONFIG_COUNT is treated the same as GIT_CONFIG_COUNT=0, namely no
pairs are processed. These environment variables will override values
in configuration files, but will be overridden by any explicit options
passed via `git -c`.
+
This is useful for cases where you want to spawn multiple git commands
with a common configuration but cannot depend on a configuration file,
for example when writing scripts.
[[EXAMPLES]]
EXAMPLES

View File

@ -472,6 +472,7 @@ static inline enum object_type object_type(unsigned int mode)
#define TEMPLATE_DIR_ENVIRONMENT "GIT_TEMPLATE_DIR"
#define CONFIG_ENVIRONMENT "GIT_CONFIG"
#define CONFIG_DATA_ENVIRONMENT "GIT_CONFIG_PARAMETERS"
#define CONFIG_COUNT_ENVIRONMENT "GIT_CONFIG_COUNT"
#define EXEC_PATH_ENVIRONMENT "GIT_EXEC_PATH"
#define CEILING_DIRECTORIES_ENVIRONMENT "GIT_CEILING_DIRECTORIES"
#define NO_REPLACE_OBJECTS_ENVIRONMENT "GIT_NO_REPLACE_OBJECTS"

View File

@ -8,6 +8,7 @@
#include "cache.h"
#include "branch.h"
#include "config.h"
#include "environment.h"
#include "repository.h"
#include "lockfile.h"
#include "exec-cmd.h"
@ -598,23 +599,73 @@ static int parse_config_env_list(char *env, config_fn_t fn, void *data)
int git_config_from_parameters(config_fn_t fn, void *data)
{
const char *env = getenv(CONFIG_DATA_ENVIRONMENT);
const char *env;
struct strbuf envvar = STRBUF_INIT;
struct strvec to_free = STRVEC_INIT;
int ret = 0;
char *envw;
char *envw = NULL;
struct config_source source;
if (!env)
return 0;
memset(&source, 0, sizeof(source));
source.prev = cf;
source.origin_type = CONFIG_ORIGIN_CMDLINE;
cf = &source;
/* sq_dequote will write over it */
envw = xstrdup(env);
ret = parse_config_env_list(envw, fn, data);
env = getenv(CONFIG_COUNT_ENVIRONMENT);
if (env) {
unsigned long count;
char *endp;
int i;
count = strtoul(env, &endp, 10);
if (*endp) {
ret = error(_("bogus count in %s"), CONFIG_COUNT_ENVIRONMENT);
goto out;
}
if (count > INT_MAX) {
ret = error(_("too many entries in %s"), CONFIG_COUNT_ENVIRONMENT);
goto out;
}
for (i = 0; i < count; i++) {
const char *key, *value;
strbuf_addf(&envvar, "GIT_CONFIG_KEY_%d", i);
key = getenv_safe(&to_free, envvar.buf);
if (!key) {
ret = error(_("missing config key %s"), envvar.buf);
goto out;
}
strbuf_reset(&envvar);
strbuf_addf(&envvar, "GIT_CONFIG_VALUE_%d", i);
value = getenv_safe(&to_free, envvar.buf);
if (!value) {
ret = error(_("missing config value %s"), envvar.buf);
goto out;
}
strbuf_reset(&envvar);
if (config_parse_pair(key, value, fn, data) < 0) {
ret = -1;
goto out;
}
}
}
env = getenv(CONFIG_DATA_ENVIRONMENT);
if (env) {
/* sq_dequote will write over it */
envw = xstrdup(env);
if (parse_config_env_list(envw, fn, data) < 0) {
ret = -1;
goto out;
}
}
out:
strbuf_release(&envvar);
strvec_clear(&to_free);
free(envw);
cf = source.prev;
return ret;

View File

@ -117,6 +117,7 @@ const char * const local_repo_env[] = {
ALTERNATE_DB_ENVIRONMENT,
CONFIG_ENVIRONMENT,
CONFIG_DATA_ENVIRONMENT,
CONFIG_COUNT_ENVIRONMENT,
DB_ENVIRONMENT,
GIT_DIR_ENVIRONMENT,
GIT_WORK_TREE_ENVIRONMENT,

View File

@ -1424,6 +1424,117 @@ test_expect_success '--config-env handles keys with equals' '
test_cmp expect actual
'
test_expect_success 'git config handles environment config pairs' '
GIT_CONFIG_COUNT=2 \
GIT_CONFIG_KEY_0="pair.one" GIT_CONFIG_VALUE_0="foo" \
GIT_CONFIG_KEY_1="pair.two" GIT_CONFIG_VALUE_1="bar" \
git config --get-regexp "pair.*" >actual &&
cat >expect <<-EOF &&
pair.one foo
pair.two bar
EOF
test_cmp expect actual
'
test_expect_success 'git config ignores pairs without count' '
test_must_fail env GIT_CONFIG_KEY_0="pair.one" GIT_CONFIG_VALUE_0="value" \
git config pair.one 2>error &&
test_must_be_empty error
'
test_expect_success 'git config ignores pairs with zero count' '
test_must_fail env \
GIT_CONFIG_COUNT=0 \
GIT_CONFIG_KEY_0="pair.one" GIT_CONFIG_VALUE_0="value" \
git config pair.one
'
test_expect_success 'git config ignores pairs exceeding count' '
GIT_CONFIG_COUNT=1 \
GIT_CONFIG_KEY_0="pair.one" GIT_CONFIG_VALUE_0="value" \
GIT_CONFIG_KEY_1="pair.two" GIT_CONFIG_VALUE_1="value" \
git config --get-regexp "pair.*" >actual &&
cat >expect <<-EOF &&
pair.one value
EOF
test_cmp expect actual
'
test_expect_success 'git config ignores pairs with zero count' '
test_must_fail env \
GIT_CONFIG_COUNT=0 GIT_CONFIG_KEY_0="pair.one" GIT_CONFIG_VALUE_0="value" \
git config pair.one >error &&
test_must_be_empty error
'
test_expect_success 'git config ignores pairs with empty count' '
test_must_fail env \
GIT_CONFIG_COUNT= GIT_CONFIG_KEY_0="pair.one" GIT_CONFIG_VALUE_0="value" \
git config pair.one >error &&
test_must_be_empty error
'
test_expect_success 'git config fails with invalid count' '
test_must_fail env GIT_CONFIG_COUNT=10a git config --list 2>error &&
test_i18ngrep "bogus count" error &&
test_must_fail env GIT_CONFIG_COUNT=9999999999999999 git config --list 2>error &&
test_i18ngrep "too many entries" error
'
test_expect_success 'git config fails with missing config key' '
test_must_fail env GIT_CONFIG_COUNT=1 GIT_CONFIG_VALUE_0="value" \
git config --list 2>error &&
test_i18ngrep "missing config key" error
'
test_expect_success 'git config fails with missing config value' '
test_must_fail env GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0="pair.one" \
git config --list 2>error &&
test_i18ngrep "missing config value" error
'
test_expect_success 'git config fails with invalid config pair key' '
test_must_fail env GIT_CONFIG_COUNT=1 \
GIT_CONFIG_KEY_0= GIT_CONFIG_VALUE_0=value \
git config --list &&
test_must_fail env GIT_CONFIG_COUNT=1 \
GIT_CONFIG_KEY_0=missing-section GIT_CONFIG_VALUE_0=value \
git config --list
'
test_expect_success 'environment overrides config file' '
test_when_finished "rm -f .git/config" &&
cat >.git/config <<-EOF &&
[pair]
one = value
EOF
GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=pair.one GIT_CONFIG_VALUE_0=override \
git config pair.one >actual &&
cat >expect <<-EOF &&
override
EOF
test_cmp expect actual
'
test_expect_success 'GIT_CONFIG_PARAMETERS overrides environment config' '
GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=pair.one GIT_CONFIG_VALUE_0=value \
GIT_CONFIG_PARAMETERS="${SQ}pair.one=override${SQ}" \
git config pair.one >actual &&
cat >expect <<-EOF &&
override
EOF
test_cmp expect actual
'
test_expect_success 'command line overrides environment config' '
GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=pair.one GIT_CONFIG_VALUE_0=value \
git -c pair.one=override config pair.one >actual &&
cat >expect <<-EOF &&
override
EOF
test_cmp expect actual
'
test_expect_success 'git config --edit works' '
git config -f tmp test.value no &&
echo test.value=yes >expect &&
@ -1769,9 +1880,11 @@ test_expect_success '--show-origin with --list' '
file:.git/config user.override=local
file:.git/config include.path=../include/relative.include
file:.git/../include/relative.include user.relative=include
command line: user.environ=true
command line: user.cmdline=true
EOF
git -c user.cmdline=true config --list --show-origin >output &&
GIT_CONFIG_COUNT=1 GIT_CONFIG_KEY_0=user.environ GIT_CONFIG_VALUE_0=true\
git -c user.cmdline=true config --list --show-origin >output &&
test_cmp expect output
'