2 files changed, 197 insertions, 0 deletions
diff --git a/c_pgms/sparse/sparse_file_alt.c b/c_pgms/sparse/sparse_file_alt.c
new file mode 100644
index 0000000..4afaa37
--- /dev/null
+++ b/c_pgms/sparse/sparse_file_alt.c
@@ -0,0 +1,46 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#define BLOCK_SIZE 4096
+
+void *buf;
+
+int main(int argc, char **argv)
+{
+        buf = malloc (512);
+        memset (buf,"a",512);
+        int fd = 0;
+        int i;
+        int sector_per_block = BLOCK_SIZE/512;
+        int block_count = 4;
+
+        if(argc != 2) {
+                printf ("Wrong usage\n USAGE: program absolute_path_to_write\n");
+                _exit (-1);
+        }
+
+        fd = open (argv[1],O_RDWR | O_CREAT,0666);
+        if (fd <= 0) {
+                printf ("file open failed\n");
+                _exit (0);
+        }
+
+        while (block_count > 0) {
+                lseek (fd, BLOCK_SIZE, SEEK_CUR);
+                block_count--;
+
+                for(i = 0; i < sector_per_block; i++)
+                        write (fd, buf, 512);
+
+                block_count--;
+        }
+
+        close(fd);
+
+        return 0;
+}
diff --git a/c_pgms/sparse/sparse_file_write.c b/c_pgms/sparse/sparse_file_write.c
new file mode 100644
index 0000000..cc95027
--- /dev/null
+++ b/c_pgms/sparse/sparse_file_write.c
@@ -0,0 +1,151 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#define UNIT_KB 1024ULL
+#define UNIT_MB UNIT_KB*1024ULL
+#define UNIT_GB UNIT_MB*1024ULL
+#define UNIT_TB UNIT_GB*1024ULL
+#define UNIT_PB UNIT_TB*1024ULL
+
+#define UNIT_KB_STRING    "KB"
+#define UNIT_MB_STRING    "MB"
+#define UNIT_GB_STRING    "GB"
+#define UNIT_TB_STRING    "TB"
+#define UNIT_PB_STRING    "PB"
+
+int
+string2bytesize (const char *str, unsigned long long *n)
+{
+        unsigned long long value = 0ULL;
+        char *tail = NULL;
+        int old_errno = 0;
+        const char *s = NULL;
+
+        if (str == NULL || n == NULL)
+        {
+                errno = EINVAL;
+                return -1;
+        }
+
+        for (s = str; *s != '\0'; s++)
+        {
+                if (isspace (*s))
+                {
+                        continue;
+                }
+                if (*s == '-')
+                {
+                        return -1;
+                }
+                break;
+        }
+
+        old_errno = errno;
+        errno = 0;
+        value = strtoull (str, &tail, 10);
+
+        if (errno == ERANGE || errno == EINVAL)
+        {
+                return -1;
+        }
+
+        if (errno == 0)
+        {
+                errno = old_errno;
+        }
+
+        if (tail[0] != '\0')
+        {
+                if (strcasecmp (tail, UNIT_KB_STRING) == 0)
+                {
+                        value *= UNIT_KB;
+                }
+                else if (strcasecmp (tail, UNIT_MB_STRING) == 0)
+                {
+                        value *= UNIT_MB;
+                }
+                else if (strcasecmp (tail, UNIT_GB_STRING) == 0)
+                {
+                        value *= UNIT_GB;
+                }
+                else if (strcasecmp (tail, UNIT_TB_STRING) == 0)
+                {
+                        value *= UNIT_TB;
+                }
+                else if (strcasecmp (tail, UNIT_PB_STRING) == 0)
+                {
+                        value *= UNIT_PB;
+                }
+
+                else
+                {
+                        return -1;
+                }
+        }
+
+        *n = value;
+
+        return 0;
+}
+
+int main (int argc, char *argv[])
+{
+        int ret = -1;
+        int fd  = -1;
+        char  *buf = "This is a string";
+        char  *filename = NULL;
+        unsigned long long size = 0;
+
+        if (argc < 2) {
+                fprintf (stderr, "Usage:./a.out <filename>\n");
+                return 2;
+        }
+
+        filename = argv[1];
+
+        fd = open (filename, O_CREAT|O_RDWR, 0644);
+        if (fd == -1) {
+                fprintf (stderr, "OPEN: cannot open the file fff. (%s)",
+                         strerror (errno));
+                return 2;
+        }
+
+	if (argc < 3)
+	        size = 5 * UNIT_GB;
+	else
+	        string2bytesize (argv[2], &size);
+
+        ret = ftruncate (fd, size);
+        if (ret == -1) {
+                fprintf (stderr, "TRUNCATE: cannot truncate the file %s. (%s)",
+                         filename, strerror (errno));
+                goto out;
+        }
+
+        ret = lseek (fd, 1048576, SEEK_SET);
+        if (ret == -1) {
+                fprintf (stderr, "LSEEK: cannot seek to the offset file fff. "
+                         "(%s)", strerror (errno));
+                goto out;
+        }
+
+        ret = write (fd, buf, strlen (buf));
+        if (ret == -1) {
+                fprintf (stderr, "WRITE: cannot write to the  file fff. (%s)",
+                         strerror (errno));
+                goto out;
+        }
+
+        ret = 0;
+out:
+        if (fd)
+                close (fd);
+
+        return ret;
+}