Implement use of PID file

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 98 insertions, 0 deletions

diff --git a/src/util.c b/src/util.c
new file mode 100644
index 0000000..cb8c155
--- /dev/null
+++ b/src/util.c
@@ -0,0 +1,98 @@
+/**
+ * gammad -- Cooperative gamma server
+ * Copyright (C) 2016  Mattias Andrée (maandree@kth.se)
+ * 
+ * This library 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 library 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 library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include "util.h"
+
+#include <sys/stat.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+
+
+/**
+ * Duplicate a memory segment
+ * 
+ * @param   src  The memory segment, must not be `NULL`
+ * @param   n    The size of the memory segment, must not be zero
+ * @return       The duplicate of the memory segment,
+ *               `NULL` on error
+ */
+void* memdup(const void* src, size_t n)
+{
+  void* dest = malloc(n);
+  if (dest == NULL)
+    return NULL;
+  memcpy(dest, src, n);
+  return dest;
+}
+
+
+/**
+ * Read an entire file
+ * 
+ * @param   fd  The file descriptor
+ * @param   n   Output for the size of the file
+ * @return      The read content, plus a NUL byte at
+ *              the end (not counted in `*n`)
+ */
+void* nread(int fd, size_t* n)
+{
+  size_t size = 32;
+  ssize_t got;
+  struct stat st;
+  char* buf = NULL;
+  char* new;
+  int saved_errno;
+  
+  *n = 0;
+  
+  if (!fstat(fd, &st))
+    size = st.st_size <= 0 ? 32 : (size_t)(st.st_size);
+  
+  buf = malloc(size + 1);
+  if (buf == NULL)
+    return NULL;
+  
+  for (;;)
+    {
+      if (*n == size)
+	{
+	  new = realloc(buf, (size <<= 1) + 1);
+	  if (new == NULL)
+	    goto fail;
+	  buf = new;
+	}
+      
+      got = read(fd, buf + *n, size - *n);
+      if (got < 0)
+	goto fail;
+      if (got == 0)
+	break;
+      *n += (size_t)got;
+    }
+  
+  buf[*n] = '\0';
+  return buf;
+ fail:
+  saved_errno = errno;
+  free(buf);
+  errno = saved_errno;
+  return NULL;
+}
+