1 files changed, 168 insertions, 0 deletions
diff --git a/src/mds-kbdc/paths.c b/src/mds-kbdc/paths.c
new file mode 100644
index 0000000..d66ae99
--- /dev/null
+++ b/src/mds-kbdc/paths.c
@@ -0,0 +1,168 @@
+/**
+ * mds — A micro-display server
+ * Copyright © 2014  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 "paths.h"
+
+#include <libmdsserver/macros.h>
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+
+
+/**
+ * Get the current working directory
+ * 
+ * @return  The current working directory
+ */
+char* curpath(void)
+{
+  static size_t cwd_size = 4096 >> 1;
+  char* cwd = NULL;
+  char* old = NULL;
+  int saved_errno;
+  
+  /* glibc offers ways to do this in just one function call,
+   * but we will not assume that glibc is used here. */
+  for (;;)
+    {
+      fail_if (xxrealloc(old, cwd, (cwd_size <<= 1) + 1, char));
+      if (getcwd(cwd, cwd_size))
+	break;
+      else
+	fail_if (errno != ERANGE);
+    }
+  
+  return cwd;
+ pfail:
+  saved_errno = errno;
+  free(old);
+  free(cwd);
+  errno = saved_errno;
+  return NULL;
+}
+
+
+/**
+ * Get the absolute path of a file
+ * 
+ * @param   path  The filename of the file
+ * @return        The file's absolute path, `NULL` on error
+ */
+char* abspath(const char* path)
+{
+  char* cwd = NULL;
+  char* buf = NULL;
+  int saved_errno, slash = 1;
+  size_t size, p;
+  
+  if (*path == '/')
+    return strdup(path);
+  
+  fail_if ((cwd = curpath(), cwd == NULL));
+  size = (p = strlen(cwd)) + strlen(path) + 2;
+  fail_if (xmalloc(buf, size + 1, char));
+  memcpy(buf, cwd, (p + 1) * sizeof(char));
+  if (buf[p - 1] != '/')
+    buf[p++] = '/';
+  
+  while (*path)
+    if (slash && (path[0] == '/'))
+      path += 1;
+    else if (slash && (path[0] == '.') && (path[1] == '/'))
+      path += 2;
+    else if (slash && (path[0] == '.') && (path[1] == '.') && (path[2] == '/'))
+      {
+	path += 3;
+	p--;
+	while (p && (buf[--p] != '/'));
+	p++;
+      }
+    else
+      {
+	buf[p++] = *path;
+	slash = (*path++ == '/');
+      }
+  
+  buf[p] = '\0';
+  
+  free(cwd);
+  return buf;
+ pfail:
+  saved_errno = errno;
+  free(cwd);
+  errno = saved_errno;
+  return NULL;
+}
+
+
+/**
+ * Get a relative path of a file
+ * 
+ * @param   path  The filename of the file
+ * @param   base  The pathname of the base directory,
+ *                `NULL` for the current working directroy
+ * @return        The file's relative path, `NULL` on error
+ */
+char* relpath(const char* path, const char* base)
+{
+  char* abs = abspath(path);
+  char* absbase = NULL;
+  char* buf = NULL;
+  char* old = NULL;
+  int saved_errno;
+  size_t p, slash = 1, back = 0;
+  
+  fail_if (abs == NULL);
+  absbase = base ? abspath(base) : curpath();
+  fail_if (absbase == NULL);
+  
+  if (absbase[strlen(absbase) - 1] != '/')
+    /* Both `abspath` and `curpath` (and `relpath`) allocates one extra slot. */
+    absbase[strlen(absbase) + 1] = '\0', absbase[strlen(absbase)] = '/';
+  
+  fprintf(stderr, "abs: %s\n", abs);
+  fprintf(stderr, "absbase: %s\n\n", absbase);
+  
+  for (p = 1; abs[p] && absbase[p] && (abs[p] == absbase[p]); p++)
+    if (abs[p] == '/')
+      slash = p + 1;
+  
+  for (p = slash; absbase[p]; p++)
+    if (absbase[p] == '/')
+      back++;
+  
+  fail_if (xmalloc(buf, back * 3 + strlen(abs + slash) + 2, char));
+  
+  for (p = 0; back--;)
+    buf[p++] = '.', buf[p++] = '.', buf[p++] = '/';
+  memcpy(buf + p, abs + slash, (strlen(abs + slash) + 1) * sizeof(char));
+  
+  free(abs);
+  free(absbase);
+  return buf;
+ pfail:
+  saved_errno = errno;
+  free(abs);
+  free(absbase);
+  free(old);
+  errno = saved_errno;
+  return NULL;
+}
+