userspace: Implement chown utility
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ebf2b16d09
commit
5df0e25c1f
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@ -4,6 +4,7 @@ set(USERSPACE_PROGRAMS
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cat
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cat-mmap
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chmod
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chown
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cp
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dd
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dhcp-client
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@ -0,0 +1,9 @@
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set(SOURCES
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main.cpp
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)
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add_executable(chown ${SOURCES})
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banan_link_library(chown ban)
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banan_link_library(chown libc)
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install(TARGETS chown OPTIONAL)
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@ -0,0 +1,109 @@
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#include <ctype.h>
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#include <errno.h>
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#include <grp.h>
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#include <pwd.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <unistd.h>
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void usage(const char* argv0, int ret)
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{
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FILE* out = (ret == 0) ? stdout : stderr;
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fprintf(out, "usage: %s [OWNER][:[GROUP]] FILE...\n", argv0);
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fprintf(out, " Change the owner and/or group of each FILE.\n");
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exit(ret);
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}
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[[noreturn]] void print_error_and_exit(const char* format, ...)
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{
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va_list args;
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va_start(args, format);
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vfprintf(stderr, format, args);
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va_end(args);
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exit(1);
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__builtin_unreachable();
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}
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const passwd* get_user(const char* string)
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{
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bool is_numeric = true;
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for (size_t i = 0; string[i] && is_numeric; i++)
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if (!isdigit(string[i]))
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is_numeric = false;
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if (is_numeric)
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return getpwuid(atoll(string));
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return getpwnam(string);
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}
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const group* get_group(const char* string)
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{
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bool is_numeric = true;
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for (size_t i = 0; string[i] && is_numeric; i++)
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if (!isdigit(string[i]))
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is_numeric = false;
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if (is_numeric)
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return getgrgid(atoll(string));
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return getgrnam(string);
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}
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int main(int argc, char** argv)
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{
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if (argc <= 2)
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usage(argv[0], 1);
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uid_t uid = -1;
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gid_t gid = -1;
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const char* owner_string = argv[1];
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const char* colon = strchr(owner_string, ':');
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if (colon == owner_string)
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{
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const auto* group = get_group(owner_string + 1);
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if (group == nullptr)
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print_error_and_exit("could not find group %s\n", owner_string + 1);
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gid = group->gr_gid;
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}
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else if (colon == nullptr)
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{
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const auto* user = get_user(owner_string);
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if (user == nullptr)
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print_error_and_exit("could not find user %s\n", owner_string);
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uid = user->pw_uid;
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}
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else
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{
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char* user_name = strndup(owner_string, colon - owner_string);
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if (user_name == nullptr)
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print_error_and_exit("strndup: %s\n", strerror(errno));
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const auto* user = get_user(user_name);
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if (user == nullptr)
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print_error_and_exit("could not find user %s\n", user_name);
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free(user_name);
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uid = user->pw_uid;
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if (colon[1] == '\0')
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gid = user->pw_gid;
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else
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{
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const auto* group = get_group(colon + 1);
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if (group == nullptr)
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print_error_and_exit("could not find group %s\n", colon + 1);
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gid = group->gr_gid;
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}
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}
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int ret = 0;
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for (int i = 2; i < argc; i++)
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{
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if (chown(argv[i], uid, gid) == -1)
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{
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perror("chown");
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ret = 1;
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}
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}
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return ret;
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}
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