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kc3-lang/gnulib/lib/modechange.c
Jim Meyering
- lib/modechange.c
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/* modechange.c -- file mode manipulation Copyright (C) 1989, 1990 Free Software Foundation, Inc. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /* Written by David MacKenzie <djm@ai.mit.edu> */ /* The ASCII mode string is compiled into a linked list of `struct modechange', which can then be applied to each file to be changed. We do this instead of re-parsing the ASCII string for each file because the compiled form requires less computation to use; when changing the mode of many files, this probably results in a performance gain. */ #include <sys/types.h> #include <sys/stat.h> #include "modechange.h" #ifdef STDC_HEADERS #include <stdlib.h> #else char *malloc (); #endif #ifndef NULL #define NULL 0 #endif #ifndef S_ISDIR #define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR) #endif /* Return newly allocated memory to hold one element of type TYPE. */ #define talloc(type) ((type *) malloc (sizeof (type))) #define isodigit(c) ((c) >= '0' && (c) <= '7') static int oatoi (); /* Return a linked list of file mode change operations created from MODE_STRING, an ASCII string that contains either an octal number specifying an absolute mode, or symbolic mode change operations with the form: [ugoa...][[+-=][rwxXstugo...]...][,...] MASKED_OPS is a bitmask indicating which symbolic mode operators (=+-) should not affect bits set in the umask when no users are given. Operators not selected in MASKED_OPS ignore the umask. Return MODE_INVALID if `mode_string' does not contain a valid representation of file mode change operations; return MODE_MEMORY_EXHAUSTED if there is insufficient memory. */ struct mode_change * mode_compile (mode_string, masked_ops) register char *mode_string; unsigned masked_ops; { struct mode_change *head; /* First element of the linked list. */ struct mode_change *change; /* An element of the linked list. */ int i; /* General purpose temporary. */ int umask_value; /* The umask value (surprise). */ unsigned short affected_bits; /* Which bits in the mode are operated on. */ unsigned short affected_masked; /* `affected_bits' modified by umask. */ unsigned ops_to_mask; /* Operators to actually use umask on. */ i = oatoi (mode_string); if (i >= 0) { if (i > 07777) return MODE_INVALID; head = talloc (struct mode_change); if (head == NULL) return MODE_MEMORY_EXHAUSTED; head->next = NULL; head->op = '='; head->flags = 0; head->value = i; head->affected = 07777; /* Affect all permissions. */ return head; } umask_value = umask (0); umask (umask_value); /* Restore the old value. */ head = NULL; --mode_string; /* One loop iteration for each "ugoa...=+-rwxXstugo...[=+-rwxXstugo...]". */ do { affected_bits = 0; ops_to_mask = 0; /* Turn on all the bits in `affected_bits' for each group given. */ for (++mode_string;; ++mode_string) switch (*mode_string) { case 'u': affected_bits |= 04700; break; case 'g': affected_bits |= 02070; break; case 'o': affected_bits |= 01007; break; case 'a': affected_bits |= 07777; break; default: goto no_more_affected; } no_more_affected: /* If none specified, affect all bits, except perhaps those set in the umask. */ if (affected_bits == 0) { affected_bits = 07777; ops_to_mask = masked_ops; } while (*mode_string == '=' || *mode_string == '+' || *mode_string == '-') { /* Add the element to the tail of the list, so the operations are performed in the correct order. */ if (head == NULL) { head = talloc (struct mode_change); if (head == NULL) return MODE_MEMORY_EXHAUSTED; change = head; } else { change->next = talloc (struct mode_change); if (change->next == NULL) { mode_free (change); return MODE_MEMORY_EXHAUSTED; } change = change->next; } change->next = NULL; change->op = *mode_string; /* One of "=+-". */ affected_masked = affected_bits; if (ops_to_mask & (*mode_string == '=' ? MODE_MASK_EQUALS : *mode_string == '+' ? MODE_MASK_PLUS : MODE_MASK_MINUS)) affected_masked &= ~umask_value; change->affected = affected_masked; change->value = 0; change->flags = 0; /* Set `value' according to the bits set in `affected_masked'. */ for (++mode_string;; ++mode_string) switch (*mode_string) { case 'r': change->value |= 00444 & affected_masked; break; case 'w': change->value |= 00222 & affected_masked; break; case 'X': change->flags |= MODE_X_IF_ANY_X; /* Fall through. */ case 'x': change->value |= 00111 & affected_masked; break; case 's': /* Set the setuid/gid bits if `u' or `g' is selected. */ change->value |= 06000 & affected_masked; break; case 't': /* Set the "save text image" bit if `o' is selected. */ change->value |= 01000 & affected_masked; break; case 'u': /* Set the affected bits to the value of the `u' bits on the same file. */ if (change->value) goto invalid; change->value = 00700; change->flags |= MODE_COPY_EXISTING; break; case 'g': /* Set the affected bits to the value of the `g' bits on the same file. */ if (change->value) goto invalid; change->value = 00070; change->flags |= MODE_COPY_EXISTING; break; case 'o': /* Set the affected bits to the value of the `o' bits on the same file. */ if (change->value) goto invalid; change->value = 00007; change->flags |= MODE_COPY_EXISTING; break; default: goto no_more_values; } no_more_values:; } } while (*mode_string == ','); if (*mode_string == 0) return head; invalid: mode_free (head); return MODE_INVALID; } /* Return file mode OLDMODE, adjusted as indicated by the list of change operations CHANGES. If OLDMODE is a directory, the type `X' change affects it even if no execute bits were set in OLDMODE. The returned value has the S_IFMT bits cleared. */ unsigned short mode_adjust (oldmode, changes) unsigned oldmode; register struct mode_change *changes; { unsigned short newmode; /* The adjusted mode and one operand. */ unsigned short value; /* The other operand. */ newmode = oldmode & 07777; for (; changes; changes = changes->next) { if (changes->flags & MODE_COPY_EXISTING) { /* Isolate in `value' the bits in `newmode' to copy, given in the mask `changes->value'. */ value = newmode & changes->value; if (changes->value & 00700) /* Copy `u' permissions onto `g' and `o'. */ value |= (value >> 3) | (value >> 6); else if (changes->value & 00070) /* Copy `g' permissions onto `u' and `o'. */ value |= (value << 3) | (value >> 3); else /* Copy `o' permissions onto `u' and `g'. */ value |= (value << 3) | (value << 6); /* In order to change only `u', `g', or `o' permissions, or some combination thereof, clear unselected bits. This can not be done in mode_compile because the value to which the `changes->affected' mask is applied depends on the old mode of each file. */ value &= changes->affected; } else { value = changes->value; /* If `X', do not affect the execute bits if the file is not a directory and no execute bits are already set. */ if ((changes->flags & MODE_X_IF_ANY_X) && !S_ISDIR (oldmode) && (newmode & 00111) == 0) value &= ~00111; /* Clear the execute bits. */ } switch (changes->op) { case '=': /* Preserve the previous values in `newmode' of bits that are not affected by this change operation. */ newmode = (newmode & ~changes->affected) | value; break; case '+': newmode |= value; break; case '-': newmode &= ~value; break; } } return newmode; } /* Free the memory used by the list of file mode change operations CHANGES. */ void mode_free (changes) register struct mode_change *changes; { register struct mode_change *next; while (changes) { next = changes->next; free (changes); changes = next; } } /* Return a positive integer containing the value of the ASCII octal number S. If S is not an octal number, return -1. */ static int oatoi (s) char *s; { register int i; if (*s == 0) return -1; for (i = 0; isodigit (*s); ++s) i = i * 8 + *s - '0'; if (*s) return -1; return i; }