Renaming all folders

09_MemoryManagement/stackallocation.c

@@ -0,0 +1,62 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <alloca.h>
+
+#define MAX_LEN 1024
+#define SYSCONF_DIR "/etc"
+
+int open_sysconf(const char *, int, int);
+
+int main(void)
+{
+	int fd = open_sysconf("/passwd", O_RDONLY, 0644);
+	if (fd == -1) {
+		perror("open");
+		return -1;
+	}
+
+	int len;
+	if ((len = lseek(fd, 0, SEEK_END)) == -1) {
+		perror("lseek");
+		return -1;
+	}
+
+	if (lseek(fd, 0, SEEK_SET) == -1) {
+		perror("lseek");
+		return -1;
+	}
+
+	char buffer[len + 1];
+	memset(buffer, 0, sizeof(buffer));
+
+	ssize_t ret;
+	size_t bytes_read_total = 0;
+	while (bytes_read_total < len && (ret = read(fd, buffer + bytes_read_total, len - bytes_read_total)) != 0) {
+		if (ret == -1) {
+			if (errno == EINTR) continue;
+			perror("read");
+			break;
+		}
+		bytes_read_total += ret;	
+	}
+	
+	buffer[bytes_read_total] = '\0';
+	printf("%s", buffer);
+
+	close(fd);
+
+	return 0;
+}
+
+int open_sysconf(const char *file, int flags, int mode)
+{
+	const char *etc = SYSCONF_DIR;
+	char *name = alloca(strlen(etc) + strlen(file) + 1);
+	strcpy(name, etc);
+	strcat(name, file);
+	return open(name, flags, mode);	
+}