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dj(1): more better comments

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Emma Tebibyte 2024-07-29 14:38:33 -06:00
parent 8d23c7fbac
commit 6c2b7b68fd
Signed by: emma
GPG Key ID: 06FA419A1698C270
1 changed files with 19 additions and 17 deletions
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src/dj.c
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@ -20,6 +20,7 @@
#include <assert.h> /* assert(3) */ #include <assert.h> /* assert(3) */
#include <errno.h> /* errno */ #include <errno.h> /* errno */
#include <fcntl.h> /* open(2) */ #include <fcntl.h> /* open(2) */
#include <stdbool.h> /* bool */
#include <stdio.h> /* fprintf(3), stderr */ #include <stdio.h> /* fprintf(3), stderr */
#include <stdlib.h> /* malloc(3), strtol(3), size_t */ #include <stdlib.h> /* malloc(3), strtol(3), size_t */
#include <string.h> /* memcpy(3), memmove(3), memset(3) */ #include <string.h> /* memcpy(3), memmove(3), memset(3) */
@ -28,8 +29,6 @@
* optarg, optind, STDIN_FILENO, STDOUT_FILENO */ * optarg, optind, STDIN_FILENO, STDOUT_FILENO */
#include <sys/stat.h> /* S_IRGRP, S_IROTH, S_IRUSR, S_IWGRP, S_IWOTH, S_IWUSR */ #include <sys/stat.h> /* S_IRGRP, S_IROTH, S_IRUSR, S_IWGRP, S_IWOTH, S_IWUSR */
extern int errno;
char *program_name = "dj"; char *program_name = "dj";
/* dj uses two structures that respectively correspond to the reading and /* dj uses two structures that respectively correspond to the reading and
@ -62,6 +61,7 @@ static int write_flags = O_WRONLY | O_CREAT;
/* Macro to check if fd is stdin or stdout */ /* Macro to check if fd is stdin or stdout */
#define fdisstd(fd) ((fd) == STDIN_FILENO || (fd) == STDOUT_FILENO) #define fdisstd(fd) ((fd) == STDIN_FILENO || (fd) == STDOUT_FILENO)
/* Completes one Io block read */
static struct Io * static struct Io *
Io_read(struct Io *io) { Io_read(struct Io *io) {
int t; int t;
@ -84,6 +84,7 @@ Io_read(struct Io *io) {
return io; return io;
} }
/* Completes one Io block write */
static struct Io * static struct Io *
Io_write(struct Io *io) { Io_write(struct Io *io) {
int t; int t;
@ -168,16 +169,16 @@ usage(char *argv0) {
int main(int argc, char *argv[]) { int main(int argc, char *argv[]) {
int align; /* low 8b used, negative if no alignment is being done */ int align; /* low 8b used, negative if no alignment is being done */
int count; /* -1 if dj(1) runs until no more reads are possible */ int count; /* -1 if dj(1) runs until no more reads are possible */
char *fmt; /* == fmt_asv (default) or fmt_human (-H) */ char *fmt; /* set to fmt_asv (default) or fmt_human (-H) */
size_t i; /* side of io being modified */ size_t i; /* side of io (in or out) being modified */
char noerror; /* 0=exits (default) 1=retries on partial reads or writes */ bool retry; /* false if exits on partial reads or writes */
struct Io io[2 /* { in, out } */]; struct Io io[2 /* { in, out } */];
/* Set defaults. */ /* Set defaults. */
align = -1; align = -1;
count = -1; count = -1;
fmt = fmt_asv; fmt = fmt_asv;
noerror = 0; retry = 0;
for (i = 0; i < (sizeof io) / (sizeof *io); ++i) { for (i = 0; i < (sizeof io) / (sizeof *io); ++i) {
io[i].bs = 1024 /* 1 KiB */; /* GNU dd(1) default; POSIX says 512B */ io[i].bs = 1024 /* 1 KiB */; /* GNU dd(1) default; POSIX says 512B */
io[i].bufuse = 0; io[i].bufuse = 0;
@ -218,8 +219,9 @@ int main(int argc, char *argv[]) {
} }
} }
return oserr(optarg, errno); /* break; */ return oserr(optarg, errno);
case 'n': noerror = 1; break; /* retry failed reads once */ /* UNREACHABLE */
case 'n': retry = 1; break; /* retry failed reads once */
case 'H': fmt = fmt_human; break; /* human-readable output */ case 'H': fmt = fmt_human; break; /* human-readable output */
case 'a': /* input buffer padding */ case 'a': /* input buffer padding */
if (optarg[0] == '\0' || optarg[1] == '\0') { if (optarg[0] == '\0' || optarg[1] == '\0') {
@ -233,12 +235,12 @@ int main(int argc, char *argv[]) {
if (c == 'c' && (count = parse(optarg)) >= 0) { break; } if (c == 'c' && (count = parse(optarg)) >= 0) { break; }
i = (c >= 'A' && c <= 'Z'); i = (c >= 'A' && c <= 'Z');
c |= 0x20; /* 0b 0010 0000 (ASCII make lowercase) */ c |= 0x20; /* 0b 0010 0000 (ASCII) make lowercase */
if ( if ( /* if -b or -s is parsed out correctly */
(c == 'b' && (io[i].bs = parse(optarg)) > 0) (c == 'b' && (io[i].bs = parse(optarg)) > 0)
|| (c == 's' && (io[i].seek = parse(optarg)) >= 0) || (c == 's' && (io[i].seek = parse(optarg)) >= 0)
) { break; } ) { break; } /* don't error */
/* FALLTHROUGH */ /* FALLTHROUGH */
default: default:
@ -277,7 +279,7 @@ int main(int argc, char *argv[]) {
(t = io[1].bufuse = MIN(io[1].bs, io[1].seek)) /* saturate block */ (t = io[1].bufuse = MIN(io[1].bs, io[1].seek)) /* saturate block */
); );
if (Io_write(&io[1])->bufuse == t && !noerror && io[1].error == 0) { if (Io_write(&io[1])->bufuse == t && !retry && io[1].error == 0) {
(void)Io_write(&io[1]); /* second chance */ (void)Io_write(&io[1]); /* second chance */
} }
@ -286,7 +288,7 @@ int main(int argc, char *argv[]) {
if (io[1].bufuse == t) { break; } /* all writes failed! */ if (io[1].bufuse == t) { break; } /* all writes failed! */
} }
io[1].bufuse = 0; io[1].bufuse = 0; /* reset after hard seek */
if (io[1].seek > 0) { /* hard seeking failed */ if (io[1].seek > 0) { /* hard seeking failed */
(void)fprintio(stderr, fmt, io); (void)fprintio(stderr, fmt, io);
@ -309,7 +311,7 @@ int main(int argc, char *argv[]) {
} }
t = io[0].bufuse; t = io[0].bufuse;
if (Io_read(&io[0])->bufuse == t && !noerror && io[0].error == 0) { if (Io_read(&io[0])->bufuse == t && !retry && io[0].error == 0) {
(void)Io_read(&io[0]); /* second chance */ (void)Io_read(&io[0]); /* second chance */
} }
@ -321,7 +323,7 @@ int main(int argc, char *argv[]) {
(void)fprintf(stderr, "%s: Partial read:\n\t", program_name); (void)fprintf(stderr, "%s: Partial read:\n\t", program_name);
(void)fprintio(stderr, fmt, io); (void)fprintio(stderr, fmt, io);
if (!noerror) { count = 1; } if (!retry) { count = 1; }
if (align >= 0) { if (align >= 0) {
/* fill the rest of the ibuf with padding */ /* fill the rest of the ibuf with padding */
@ -380,7 +382,7 @@ int main(int argc, char *argv[]) {
t = io[1].bufuse; t = io[1].bufuse;
if (Io_write(&io[1])->bufuse == t if (Io_write(&io[1])->bufuse == t
&& !noerror && !retry
&& io[1].error == 0) { && io[1].error == 0) {
(void)Io_write(&io[1]); /* second chance */ (void)Io_write(&io[1]); /* second chance */
} }
@ -402,7 +404,7 @@ int main(int argc, char *argv[]) {
(void)fprintf(stderr, "%s: Partial write:\n\t", program_name); (void)fprintf(stderr, "%s: Partial write:\n\t", program_name);
(void)fprintio(stderr, fmt, io); (void)fprintio(stderr, fmt, io);
if(!noerror) { count = 1; } if(!retry) { count = 1; }
} }
} }
} }