coreutils
General Software Utilities
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coreutils/src/util/mode.c (84 lines, 2.3 KiB) -rw-r--r-- file download
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// util/mode.c, version 1.0.3
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// Mode source file from libutil
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// Copyright (C) 2020, Jakob Wakeling
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// MIT Licence
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/*
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	TODO Handle copying permissions
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*/
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#include "mode.h"
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#include <sys/types.h>
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#include <stdio.h>
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#include <stdlib.h>
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static inline int getop(char **s);
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static inline mode_t getref(char **s);
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/* Parse an octal or symbolic mode string */
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chmod_t *strmode(char *str) {
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	char *s = str; chmod_t *m; mode_t mode = 0; size_t i;
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	// Try and parse an octal mode
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	for (register mode_t d; *s >= '0' && *s <= '7'; ++s) {
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		d = *s - '0'; if (mode > (07777 - d) / 8) { break; }
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		mode = mode * 8 + d;
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	}
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	if (!*s) {
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		m = (chmod_t *)malloc(2 * sizeof (*m));
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		// Construct a chmod_t from the octal mode and return it
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		m[0].flag = MF_NORM; m[1].flag = MF_NULL;
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		m[0].op = '='; m[0].ref = M_ALL; m[0].mod = mode;
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		return m;
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	}
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	// If the octal mode is invalid return NULL
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	else if (s != str) { return NULL; }
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	// Allocate necesary memory for chmod_t array
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	for (i = 1; *s; ++s) { i += (*s == '+' || *s == '-' || *s == '='); }
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	m = (chmod_t *)malloc((i + 1) * sizeof (*m)); s = str; m[i].flag = MF_NULL;
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	i = 0; do { // Parse each part of the symbolic mode string
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		for (mode_t ref = getref(&s); ((m[i].op = getop(&s))); ++i) {
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			m[i].flag = MF_NORM; m[i].ref = ref;
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			// Process the next mode
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			for (m[i].mod = 0;;) switch (*s) {
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				case 'r': { m[i].mod |= M_RD; ++s; continue; }
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				case 'w': { m[i].mod |= M_WR; ++s; continue; }
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				case 'x': { m[i].mod |= M_EX; ++s; continue; }
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				case 'X': { m[i].flag = MF_XIFX; ++s; continue; }
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				case 's': { m[i].mod |= M_ID; ++s; continue; }
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				case 't': { m[i].mod |= M_ST; ++s; continue; }
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				default: { goto end; }
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			} end:;
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		}
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	} while (*s++ == ',' && *s);
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	// If the symbolic mode is invalid return NULL
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	if (*--s) { free(m); return NULL; } return m;
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}
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/* Process and return next operator */
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static inline int getop(char **s) {
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	switch (**s) { case '+': case '-': case '=': { return *(*s)++; }}
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	return 0;
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}
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/* Process and return next reference */
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static inline mode_t getref(char **s) {
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	for (mode_t ref = 0;;) switch (**s) {
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	case 'u': { ref |= M_USR; ++*s; continue; }
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	case 'g': { ref |= M_GRP; ++*s; continue; }
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	case 'o': { ref |= M_OTH; ++*s; continue; }
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	case 'a': { ref |= M_ALL; ++*s; continue; }
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	default: { return ref; }
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	}
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}
 
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