402 lines
9.4 KiB
C
402 lines
9.4 KiB
C
/*
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* Copyright (c) 2014, 2020 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* chmod.c
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* Change file permissions.
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <assert.h>
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#include <dirent.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <inttypes.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.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 <unistd.h>
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static const int FLAG_CHANGES = 1 << 0;
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static const int FLAG_VERBOSE = 1 << 1;
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static const int FLAG_RECURSIVE = 1 << 2;
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static const int FLAG_NOFOLLOW = 1 << 3;
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enum symderef
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{
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SYMDEREF_NONE,
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SYMDEREF_ARGUMENTS,
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SYMDEREF_ALWAYS,
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SYMDEREF_DEFAULT,
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};
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static bool is_octal_string(const char* str)
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{
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if ( !str[0] )
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return false;
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for ( size_t i = 0; str[i]; i++ )
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if ( !('0' <= str[i] && str[i] <= '7') )
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return false;
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return true;
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}
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static mode_t execute_modespec(const char* str,
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mode_t mode,
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mode_t type,
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mode_t umask)
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{
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if ( is_octal_string(str) )
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{
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errno = 0;
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uintmax_t input = strtoumax((char*) str, NULL, 8);
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if ( errno == ERANGE )
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return (mode_t) -1;
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if ( input & ~((uintmax_t) 07777) )
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return (mode_t) -1;
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return (mode_t) input;
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}
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size_t index = 0;
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do
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{
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mode_t who_mask = 01000;
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while ( true )
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{
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if ( str[index] == 'u' && (index++, true) )
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who_mask |= 04700;
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else if ( str[index] == 'g' && (index++, true) )
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who_mask |= 02070;
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else if ( str[index] == 'o' && (index++, true) )
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who_mask |= 00007;
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else if ( str[index] == 'a' && (index++, true) )
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who_mask |= 06777;
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else
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break;
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}
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if ( !(who_mask & 0777) )
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who_mask |= 06777 & ~umask;
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do
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{
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char op;
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switch ( (op = str[index++]) )
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{
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case '+': break;
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case '-': break;
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case '=': break;
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default: return (mode_t) -1;
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};
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mode_t operand = 0;
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if ( str[index] == 'u' || str[index] == 'g' || str[index] == 'o' )
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{
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char permcopy = str[index++];
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switch ( permcopy )
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{
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case 'u': operand = mode >> 6 & 07; break;
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case 'g': operand = mode >> 3 & 07; break;
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case 'o': operand = mode >> 0 & 07; break;
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default: __builtin_unreachable();
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};
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operand = operand << 0 | operand << 3 | operand << 6;
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switch ( permcopy )
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{
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case 'u': if ( mode & 04000) operand |= 06000; break;
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case 'g': if ( mode & 02000) operand |= 06000; break;
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};
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who_mask &= ~((mode_t) 01000);
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}
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else
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{
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bool unknown = false;
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do
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{
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switch ( str[index] )
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{
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case 'r': operand |= 00444; break;
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case 'w': operand |= 00222; break;
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case 'x': operand |= 00111; break;
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case 'X':
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if ( S_ISDIR(type) || (mode & 0111) )
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operand |= 00111;
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break;
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case 's': operand |= 06000; break;
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case 't': operand |= 00000; break;
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default: unknown = true; break;
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}
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} while ( !unknown && (index++, true) );
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}
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switch ( op )
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{
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case '+': mode |= (operand & who_mask); break;
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case '-': mode &= ~(operand & who_mask); break;
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case '=': mode = (mode & ~who_mask) | (operand & who_mask); break;
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default: __builtin_unreachable();
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}
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} while ( str[index] == '+' ||
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str[index] == '-' ||
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str[index] == '=' );
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} while ( str[index] == ',' && (index++, true) );
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if ( str[index] )
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return (mode_t) -1;
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return mode;
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}
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static bool is_valid_modespec(const char* str)
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{
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return execute_modespec(str, 0, 0, 0) != (mode_t) -1;
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}
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static bool do_chmod_directory(int fd,
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const char* path,
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const char* modespec,
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int flags,
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enum symderef symderef);
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static bool do_chmod(int dirfd,
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const char* relpath,
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const char* path,
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const char* modespec,
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int flags,
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enum symderef symderef)
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{
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bool success = true;
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int fd_open_flags = O_RDONLY;
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if ( symderef == SYMDEREF_NONE )
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fd_open_flags |= O_SYMLINK_NOFOLLOW;
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int fd = openat(dirfd, relpath, fd_open_flags);
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if ( fd < 0 )
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{
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warn("%s", path);
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return false;
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}
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struct stat st;
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if ( fstat(fd, &st) < 0 )
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{
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warn("stat: %s", path);
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close(fd);
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return false;
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}
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if ( S_ISLNK(st.st_mode) )
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{
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close(fd);
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return true;
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}
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mode_t old_mode = st.st_mode & 07777;
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mode_t new_mode = execute_modespec(modespec, old_mode, st.st_mode, getumask());
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assert(new_mode != (mode_t) -1);
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if ( fchmod(fd, new_mode) < 0 )
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{
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warn("changing permissions: %s", path);
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success = false;
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}
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else
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{
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mode_t naive_mode = execute_modespec(modespec, old_mode, st.st_mode, 0);
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assert(naive_mode != (mode_t) -1);
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if ( new_mode & ~naive_mode )
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warnx("%s: new permissions are %jo, not %jo",
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path, (uintmax_t) new_mode, (uintmax_t) naive_mode);
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if ( (flags & FLAG_VERBOSE) ||
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(old_mode != new_mode && (flags & FLAG_CHANGES)) )
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{
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if ( old_mode == new_mode )
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printf("mode of `%s' retained as %jo\n",
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path, (uintmax_t) new_mode);
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else
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printf("mode of `%s' changed from %jo to %jo\n",
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path, (uintmax_t) old_mode, (uintmax_t) new_mode);
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}
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}
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if ( S_ISDIR(st.st_mode) && (flags & FLAG_RECURSIVE) )
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{
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if ( !do_chmod_directory(fd, path, modespec, flags, symderef) )
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success = false;
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}
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close(fd);
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return success;
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}
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static bool do_chmod_directory(int fd,
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const char* path,
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const char* modespec,
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int flags,
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enum symderef symderef)
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{
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if ( symderef == SYMDEREF_ARGUMENTS )
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symderef = SYMDEREF_NONE;
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int fd_copy = dup(fd);
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if ( fd_copy < 0 )
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{
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warn("dup: %s", path);
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return false;
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}
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DIR* dir = fdopendir(fd_copy);
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if ( !dir )
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{
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warn("fdopendir: %s", path);
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close(fd_copy);
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return false;
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}
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const char* joiner = "/";
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size_t path_length = strlen(path);
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if ( path_length && path[path_length - 1] == '/' )
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joiner = "";
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bool success = true;
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struct dirent* entry;
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while ( (errno = 0, entry = readdir(dir)) )
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{
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if ( !strcmp(entry->d_name, ".") || !strcmp(entry->d_name, "..") )
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continue;
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char* entry_path;
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if ( asprintf(&entry_path, "%s%s%s", path, joiner, entry->d_name) < 0 )
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{
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warn("asprintf: `%s%s%s'", path, joiner, entry->d_name);
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success = false;
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continue;
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}
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if ( !do_chmod(fd, entry->d_name, entry_path, modespec, flags, symderef) )
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success = false;
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free(entry_path);
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}
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if ( errno != 0 )
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{
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warn("reading directory: %s", path);
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closedir(dir);
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return false;
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}
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closedir(dir);
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return success;
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}
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static bool is_ambiguous_option(const char* str)
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{
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if ( str[0] != '-' )
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return false;
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if ( str[1] == '-' )
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return false;
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return is_valid_modespec(str);
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}
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static void compact_arguments(int* argc, char*** argv)
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{
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for ( int i = 0; i < *argc; i++ )
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{
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while ( i < *argc && !(*argv)[i] )
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{
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for ( int n = i; n < *argc; n++ )
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(*argv)[n] = (*argv)[n+1];
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(*argc)--;
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}
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}
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}
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int main(int argc, char* argv[])
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{
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int flags = 0;
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enum symderef symderef = SYMDEREF_DEFAULT;
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for ( int i = 1; i < argc; i++ )
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{
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const char* arg = argv[i];
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if ( arg[0] != '-' || !arg[1] )
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continue;
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if ( is_ambiguous_option(arg) )
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continue;
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argv[i] = NULL;
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if ( !strcmp(arg, "--") )
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break;
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if ( arg[1] != '-' )
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{
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char c;
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while ( (c = *++arg) ) switch ( c )
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{
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case 'c': flags |= FLAG_CHANGES; break;
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case 'h': flags |= FLAG_NOFOLLOW; break;
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case 'H': symderef = SYMDEREF_ARGUMENTS; break;
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case 'L': symderef = SYMDEREF_ALWAYS; break;
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case 'P': symderef = SYMDEREF_NONE; break;
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case 'R': flags |= FLAG_RECURSIVE; break;
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case 'v': flags |= FLAG_VERBOSE; break;
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default:
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errx(1, "unknown option -- '%c'", c);
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}
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}
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else if ( !strcmp(arg, "--changes") )
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flags |= FLAG_CHANGES;
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else if ( !strcmp(arg, "--verbose") )
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flags |= FLAG_VERBOSE;
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else if ( !strcmp(arg, "--recursive") )
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flags |= FLAG_RECURSIVE;
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else
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errx(1, "unknown option: %s", arg);
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}
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compact_arguments(&argc, &argv);
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if ( (flags & FLAG_RECURSIVE) && (flags & FLAG_NOFOLLOW) )
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errx(1, "the -R and -h options are mutually incompatible");
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if ( flags & FLAG_RECURSIVE )
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{
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if ( symderef == SYMDEREF_DEFAULT )
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symderef = SYMDEREF_NONE;
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}
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else
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symderef = flags & FLAG_NOFOLLOW ? SYMDEREF_NONE : SYMDEREF_ALWAYS;
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if ( argc == 1 )
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errx(1, "missing operand");
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const char* modespec = argv[1];
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if ( !is_valid_modespec(modespec) )
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errx(1, "invalid mode: `%s'", modespec);
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if ( argc == 2 )
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errx(1, "missing operand after `%s'", modespec);
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bool success = true;
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for ( int i = 2; i < argc; i++ )
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{
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const char* arg = argv[i];
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if ( !do_chmod(AT_FDCWD, arg, arg, modespec, flags, symderef) )
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success = false;
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}
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return success ? 0 : 1;
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}
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