custom-env: Add helper to parse combined env/arg strings

Users like desktop-shell want to parse a provided string containing a
combination of environment and arg, e.g.: ENV=stuff /path/to/thing --good

Add support to custom-env for parsing this, with tests, so we can delete
the custom implementation inside desktop-shell.

Signed-off-by: Daniel Stone <daniels@collabora.com>
This commit is contained in:
Daniel Stone 2022-07-12 16:21:39 +01:00 committed by Pekka Paalanen
parent e568a025e1
commit 2cdb473690
3 changed files with 136 additions and 0 deletions

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@ -25,6 +25,9 @@
#include "config.h"
#include <assert.h>
#include <ctype.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@ -154,6 +157,84 @@ custom_env_set_env_var(struct custom_env *env, const char *name, const char *val
assert(*ep);
}
/**
* Add information from a parsed exec string to a custom_env
*
* An 'exec string' is a string in the format:
* ENVFOO=bar ENVBAR=baz /path/to/exec --arg anotherarg
*
* This function will parse such a string and add the specified environment
* variables (in the format KEY=value) up until it sees a non-environment
* string, after which point every entry will be interpreted as a new
* argument.
*
* Entries are space-separated; there is no support for quoting.
*/
void
custom_env_add_from_exec_string(struct custom_env *env, const char *exec_str)
{
char *dup_path = strdup(exec_str);
char *start = dup_path;
assert(dup_path);
/* Build the environment array (if any) by handling any number of
* equal-separated key=value at the start of the string, split by
* spaces; uses "foo=bar baz=quux meh argh" as the example, where
* "foo=bar" and "baz=quux" should go into the environment, and
* "meh" should be executed with "argh" as its first argument */
while (*start) {
char *k = NULL, *v = NULL;
char *p;
/* Leaves us with "foo\0bar baz=quux meh argh", with k pointing
* to "foo" and v pointing to "bar baz=quux meh argh" */
for (p = start; *p && !isspace(*p); p++) {
if (*p == '=') {
*p++ = '\0';
k = start;
v = p;
break;
}
}
if (!v)
break;
/* Walk to the next space or NUL, filling any trailing spaces
* with NUL, to give us "foo\0bar\0\0baz=quux meh argh".
* k will point to "foo", v will point to "bar", and
* start will point to "baz=quux meh argh". */
while (*p && !isspace(*p))
p++;
while (*p && isspace(*p))
*p++ = '\0';
start = p;
custom_env_set_env_var(env, k, v);
}
/* Now build the argv array by splitting on spaces */
while (*start) {
char *p;
bool valid = false;
for (p = start; *p && !isspace(*p); p++)
valid = true;
if (!valid)
break;
while (*p && isspace(*p))
*p++ = '\0';
custom_env_add_arg(env, start);
start = p;
}
free(dup_path);
}
char *const *
custom_env_get_envp(struct custom_env *env)
{

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@ -84,6 +84,9 @@ custom_env_set_env_var(struct custom_env *env, const char *name, const char *val
void
custom_env_add_arg(struct custom_env *env, const char *arg);
void
custom_env_add_from_exec_string(struct custom_env *env, const char *exec_str);
char *const *
custom_env_get_envp(struct custom_env *env);

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@ -104,3 +104,55 @@ TEST(basic_env_arg)
assert(env.arg_finalized);
custom_env_fini(&env);
}
struct test_str {
const char *exec_str;
char * const *envp;
char * const *argp;
};
static struct test_str str_tests[] = {
{
.exec_str = "ENV1=1 ENV2=owt two-arghs",
.envp = (char * const []) { "ENV1=1", "ENV2=owt", "ENV3=three", NULL },
.argp = (char * const []) { "two-arghs", NULL },
},
{
.exec_str = "ENV2=owt one-argh",
.envp = (char * const []) { "ENV1=one", "ENV2=owt", "ENV3=three", NULL },
.argp = (char * const []) { "one-argh", NULL },
},
{
.exec_str = "FOO=bar one-argh-again",
.envp = (char * const []) { "ENV1=one", "ENV2=two", "ENV3=three", "FOO=bar", NULL },
.argp = (char * const []) { "one-argh-again", NULL },
},
{
.exec_str = "ENV1=number=7 one-argh-eq",
.envp = (char * const []) { "ENV1=number=7", "ENV2=two", "ENV3=three", NULL },
.argp = (char * const []) { "one-argh-eq", NULL },
},
{
.exec_str = "no-arg-h",
.envp = DEFAULT_ENVP,
.argp = (char * const []) { "no-arg-h", NULL },
},
{
.exec_str = "argh-w-arg argequals=thing plainarg ",
.envp = DEFAULT_ENVP,
.argp = (char * const []) { "argh-w-arg", "argequals=thing", "plainarg", NULL },
},
};
TEST_P(env_parse_string, str_tests)
{
struct custom_env env;
struct test_str *test = data;
testlog("checking exec_str '%s'\n", test->exec_str);
custom_env_init_from_environ(&env);
custom_env_add_from_exec_string(&env, test->exec_str);
ASSERT_STR_ARRAY_MATCH("envp", custom_env_get_envp(&env), test->envp);
ASSERT_STR_ARRAY_MATCH("argp", custom_env_get_argp(&env), test->argp);
custom_env_fini(&env);
}