implement humanmode

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 75 insertions, 0 deletions

diff --git a/src/slibc-human/humanmode.c b/src/slibc-human/humanmode.c
new file mode 100644
index 0000000..57b1534
--- /dev/null
+++ b/src/slibc-human/humanmode.c
@@ -0,0 +1,75 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.
+ */
+#include <slib-human.h>
+#include <stdlib.h>
+#include <errno.h>
+
+
+
+/**
+ * Convert file permission from machine representation to human representation.
+ * 
+ * @param   buffer  Sufficiently large buffer for the output, or `NULL`.
+ *                  18 characters is always sufficient, regardless of `mode`.
+ * @param   perm    Machine representation of the permissions, will be masked with 07777.
+ * @param   mode    Representation style, 0 for default.
+ * @return          Human representation of the file permissions, `NULL` on error.
+ *                  On success, the caller is responsible for deallocating the
+ *                  returned pointer, if and only if `buffer` is `NULL`.
+ * 
+ * @throws  EINVAL  If `mode` is invalid.
+ * @throws  ENOMEM  The process cannot allocate more memory.
+ */
+char* humanmode(char* restrict buffer, mode_t perm, enum humanmode_mode mode)
+{
+  mode_t perm_ = perm | (mode != MACHINEMODE_MASK ? 07777 : 0);
+  int name = mode & MACHINEMODE_MASK;
+  char* w;
+  
+  if (mode & ~3)
+    return errno = EINVAL, NULL;
+  if (!mode)
+    mode = MACHINEMODE_STAT;
+  
+  if (buffer == NULL)
+    buffer = malloc((mode == MACHINEMODE_STAT ? 10 : 18) * sizeof(char));
+  if (buffer == NULL)
+    return NULL;
+  w = buffer;
+  
+  if (name)                  *w++ = 'u', *w++ = '=';
+  if (perm_ & S_IRUSR)       *w++ = (perm & S_IRUSR) ? 'r' : '-';
+  if (perm_ & S_IWUSR)       *w++ = (perm & S_IWUSR) ? 'w' : '-';
+  if (perm & S_ISUID)        *w++ = (perm & S_IXUSR) ? 's' : 'S';
+  else if (perm_ & S_IXUSR)  *w++ = (perm & S_IXUSR) ? 'x' : '-';
+  
+  if (name)                  *w++ = ',', *w++ = 'g', *w++ = '=';
+  if (perm_ & S_IRGRP)       *w++ = (perm & S_IRGRP) ? 'r' : '-';
+  if (perm_ & S_IWGRP)       *w++ = (perm & S_IWGRP) ? 'w' : '-';
+  if (perm & S_ISGID)        *w++ = (perm & S_IXGRP) ? 's' : 'S';
+  else if (perm_ & S_IXGRP)  *w++ = (perm & S_IXGRP) ? 'x' : '-';
+  
+  if (name)                  *w++ = ',', *w++ = 'o', *w++ = '=';
+  if (perm_ & S_IROTH)       *w++ = (perm & S_IROTH) ? 'r' : '-';
+  if (perm_ & S_IWOTH)       *w++ = (perm & S_IWOTH) ? 'w' : '-';
+  if (perm & S_ISVTX)        *w++ = (perm & S_IXOTH) ? 't' : 'T';
+  else if (perm_ & S_IXOTH)  *w++ = (perm & S_IXOTH) ? 'x' : '-';
+  
+  return *w = 0, buffer;
+}
+