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/*
* Copyright 2023 Huawei Cloud Computing Technology Co., Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/* usage: ./expand_exec [VARS...] -- ARGS... */
int main(int argc, const char *argv[]) {
char **outv;
const char **varv;
int i, j, varc, sep = 0, retval = 0;
for (i = 1; i < argc; ++i)
if (strcmp(argv[i], "--") == 0) {
sep = i;
break;
}
varc = sep - 1;
argc -= sep + 1;
if (sep == 0 || argc < 1)
return 1; /* error: missing sep or args */
varv = &argv[1];
argv = &argv[sep + 1];
outv = (char **)calloc((size_t)(argc + 1), sizeof(char *));
for (i = 0; i < argc; ++i) { /* iterate ARGS */
const char *arg = argv[i];
size_t arg_pos = 0, arg_len = strlen(arg);
size_t out_pos = 0, out_len = arg_len;
size_t str_pos = 0, str_len = 0;
char *out = (char *)calloc((size_t)(out_len + 1), sizeof(char));
for (; arg_pos < arg_len; ++arg_pos) {
if (strncmp(&arg[arg_pos], "$(", 2) == 0) {
const char *start = &arg[arg_pos + 2];
const char *end = strchr(start, ')');
if (end == NULL) {
retval = 2; /* error: unterminated $(VAR) expression */
free(out);
goto cleanup;
}
for (j = 0; j < varc; ++j) { /* lookup VAR */
const char *var = varv[j];
size_t len_var = strlen(var);
if ((size_t)(end - start) != len_var)
continue;
if (strncmp(&arg[arg_pos + 2], var, len_var) == 0) {
size_t val_len, out_len_new;
const char *val = getenv(var);
if (val == NULL)
val = "";
val_len = strlen(val);
out_len_new = out_pos + str_len + val_len;
if (out_len_new > out_len) {
out = (char *)realloc(out, out_len_new + 1);
out_len = out_len_new;
}
strncat(out, &arg[str_pos], str_len); /* concat preceding substr */
strncat(out, val, val_len); /* concat variable value */
arg_pos += len_var + 2;
out_pos += str_len + val_len;
str_pos = arg_pos + 1;
str_len = 0;
break;
}
}
if (j != varc)
continue; /* success */
}
++str_len;
}
if (str_len > 0) {
if (out_pos + str_len > out_len) {
out = (char *)realloc(out, out_pos + str_len + 1);
}
strncat(out, &arg[str_pos], str_len);
}
outv[i] = out;
}
execvp(outv[0], outv);
retval = 3; /* error: exec failed */
cleanup:
for (i = 0; i < argc; ++i)
if (outv[i] != NULL)
free(outv[i]);
free(outv);
return retval;
}
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