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file_ops begun

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This commit is contained in:
Perry Kivolowitz 2022-12-25 14:53:15 -06:00
parent cc00e6fa56
commit 5e63912d39
3 changed files with 37 additions and 13 deletions
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33
section_1/funcs/file_ops.s
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@ -19,16 +19,26 @@ fd .req w28
main: stp x29, x30, [sp, -16]!
stp x27, x28, [sp, -16]!
bl open_file
cbz x0, 1f
// w0 will contain either the file descriptor of the new
// file or -1 for a failure. Note that the value in w0
// has also been copied to "fd" - a register alias.
cmp w0, wzr
bge 1f
// If we get here, the open has failed. Use perror() to
// print a meaningful error and exit.
// print a meaningful error and branch to exit. The return
// code of the program will be set to non-zero inside open_fail.
bl open_fail
b 99f
1: // When we get here, the file is open.
1: // When we get here, the file is open. Write some data to it.
// If write_file returns non-zero, it signifies an error. If
// so, branch to the file closing code since the file is open.
// The error message will be printed in write_data.
bl write_data
cbnz w0, 10f
// When we get here, we are done. Close the file.
mov w0, fd
10: mov w0, fd
bl close
mov retval, wzr
@ -45,8 +55,12 @@ main: stp x29, x30, [sp, -16]!
open_file:
stp x29, x30, [sp, -16]!
ldp x29, x30, [sp], 16
mov x0, 1
ldr x0, =fname
mov w1, 0102
mov w2, 0600
bl open
mov fd, w0
ldp x29, x30, [sp], 16
ret
@ -62,9 +76,14 @@ open_fail:
ldp x29, x30, [sp], 16
ret
write_data:
stp x29, x30, [sp, -16]!
ldp x29, x30, [sp], 16
ret
.data
prog: .asciz "file_ops"
fname: .asciz "test.txt"
txt: .asciz "some data\n"
txt_s: .word txt_s - txt - 1 // strlen(txt)
.end

0
section_1/funcs/foo.c → section_1/funcs/foo2.c
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17
section_1/funcs/fops.c
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@ -6,8 +6,8 @@
int main(int argc, char **argv) {
char * fname = "test.txt";
char * p_legend = NULL;
int fd = open(fname, O_RDWR | O_CREAT, 00600);
int retval = 0;
int fd = open(fname, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
int retval = 0;
off_t seek_return;
char buffer[80];
@ -15,7 +15,10 @@ int main(int argc, char **argv) {
p_legend = fname;
goto out;
} else {
printf("Flags used to open file: %o\n", O_RDWR | O_CREAT);
printf("Flags used to open file: 0%o 0%o\n",
O_RDWR | O_CREAT,
S_IRUSR | S_IWUSR
);
for (int counter = 0; counter < 10; counter++) {
if (write(fd, "data\n", 5) != 5) {
p_legend = "On writing";
@ -39,10 +42,12 @@ int main(int argc, char **argv) {
out: if (fd >= 0) {
close(fd);
if (unlink(fname)) {
/* if (unlink(fname)) {
p_legend = "On unlinking";
}
}
} else {
printf("All went well. File is deleted.\n");
}
*/ }
if (p_legend != NULL) {
perror(p_legend);