write homework 5

diff --git a/assgn5/Makefile b/assgn5/Makefile
new file mode 100644 (file)
index 0000000..8034288
--- /dev/null
+++ b/assgn5/Makefile
@@ -0,0 +1,9 @@
+PHONY: all
+
+CC=/usr/bin/gcc
+
+all:
+       $(CC) -Wall -Werror -Wextra -pedantic copy.c -o copy -Wno-unused-parameter -Wno-unused
+
+debug:
+       $(CC) -g -O0 -Wall -Werror -Wextra -pedantic copy.c -o copy -Wno-unused-parameter -Wno-unused

diff --git a/assgn5/assgn5.tar.gz b/assgn5/assgn5.tar.gz
new file mode 100644 (file)
index 0000000..644b24a
Binary files /dev/null and b/assgn5/assgn5.tar.gz differ

diff --git a/assgn5/copy.c b/assgn5/copy.c
new file mode 100644 (file)
index 0000000..0a3c8d5
--- /dev/null
+++ b/assgn5/copy.c
@@ -0,0 +1,78 @@
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <sys/stat.h>
+
+int main(int argc, char *argv[]) {
+
+       int cur, flag_append, flag_force;
+       int fd_from, fd_to, mode;
+       char buf[1];
+
+       flag_append = 0;
+       flag_force  = 0;
+
+       while((cur = getopt(argc, argv, "af")) != -1) {
+               switch(cur) {
+
+                       case 'a':
+                               flag_append = 1;
+                               break;
+
+                       case 'f':
+                               flag_force = 1;
+                               break;
+
+                       default:
+                               printf("invalid argument\n");
+                               return 1;
+               }
+       }
+
+       if(argc - optind != 2) {
+
+               printf("invalid number of args\n");
+               return 1;
+
+       } else if(flag_append && flag_force) {
+
+               printf("cannot simultaneously specify overwrite and append\n");
+               return 1;
+       }
+
+       if(access(argv[optind + 1], F_OK) != -1 && !flag_append && !flag_force) {
+
+               printf("destination file already exists, pass -f to overwrite\n");
+               return 1;
+       }
+
+       if(flag_force)       mode = O_TRUNC;
+       else if(flag_append) mode = O_APPEND;
+       else                 mode = O_CREAT;
+
+       fd_from = open(argv[optind], O_RDONLY);
+       fd_to   = open(argv[optind + 1], mode | O_WRONLY, S_IRWXU);
+
+       if(fd_from == -1) {
+
+               printf("could not open source file\n");
+               return 1;
+
+       } else if(fd_to == -1 && !flag_force && !flag_append) {
+
+               printf("could not create new destination file\n");
+               return 1;
+
+       } else if(fd_to == -1) {
+
+       }
+
+       while(read(fd_from, buf, 1) == 1)
+               write(fd_to, buf, 1);
+
+       close(fd_from);
+       close(fd_to);
+
+       return 0;
+}