From 6c2b7b68fd503e75f86129b0ab238cad7e148695 Mon Sep 17 00:00:00 2001 From: emma Date: Mon, 29 Jul 2024 14:38:33 -0600 Subject: [PATCH] dj(1): more better comments --- src/dj.c | 36 +++++++++++++++++++----------------- 1 file changed, 19 insertions(+), 17 deletions(-) diff --git a/src/dj.c b/src/dj.c index 17f406c..d6f5fde 100644 --- a/src/dj.c +++ b/src/dj.c @@ -20,6 +20,7 @@ #include /* assert(3) */ #include /* errno */ #include /* open(2) */ +#include /* bool */ #include /* fprintf(3), stderr */ #include /* malloc(3), strtol(3), size_t */ #include /* memcpy(3), memmove(3), memset(3) */ @@ -28,8 +29,6 @@ * optarg, optind, STDIN_FILENO, STDOUT_FILENO */ #include /* S_IRGRP, S_IROTH, S_IRUSR, S_IWGRP, S_IWOTH, S_IWUSR */ -extern int errno; - char *program_name = "dj"; /* 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 */ #define fdisstd(fd) ((fd) == STDIN_FILENO || (fd) == STDOUT_FILENO) +/* Completes one Io block read */ static struct Io * Io_read(struct Io *io) { int t; @@ -84,6 +84,7 @@ Io_read(struct Io *io) { return io; } +/* Completes one Io block write */ static struct Io * Io_write(struct Io *io) { int t; @@ -168,16 +169,16 @@ usage(char *argv0) { int main(int argc, char *argv[]) { 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 */ - char *fmt; /* == fmt_asv (default) or fmt_human (-H) */ - size_t i; /* side of io being modified */ - char noerror; /* 0=exits (default) 1=retries on partial reads or writes */ + char *fmt; /* set to fmt_asv (default) or fmt_human (-H) */ + size_t i; /* side of io (in or out) being modified */ + bool retry; /* false if exits on partial reads or writes */ struct Io io[2 /* { in, out } */]; /* Set defaults. */ align = -1; count = -1; fmt = fmt_asv; - noerror = 0; + retry = 0; for (i = 0; i < (sizeof io) / (sizeof *io); ++i) { io[i].bs = 1024 /* 1 KiB */; /* GNU dd(1) default; POSIX says 512B */ io[i].bufuse = 0; @@ -218,8 +219,9 @@ int main(int argc, char *argv[]) { } } - return oserr(optarg, errno); /* break; */ - case 'n': noerror = 1; break; /* retry failed reads once */ + return oserr(optarg, errno); + /* UNREACHABLE */ + case 'n': retry = 1; break; /* retry failed reads once */ case 'H': fmt = fmt_human; break; /* human-readable output */ case 'a': /* input buffer padding */ 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; } 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 == 's' && (io[i].seek = parse(optarg)) >= 0) - ) { break; } + ) { break; } /* don't error */ /* FALLTHROUGH */ default: @@ -277,7 +279,7 @@ int main(int argc, char *argv[]) { (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 */ } @@ -286,7 +288,7 @@ int main(int argc, char *argv[]) { 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 */ (void)fprintio(stderr, fmt, io); @@ -309,7 +311,7 @@ int main(int argc, char *argv[]) { } 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 */ } @@ -321,7 +323,7 @@ int main(int argc, char *argv[]) { (void)fprintf(stderr, "%s: Partial read:\n\t", program_name); (void)fprintio(stderr, fmt, io); - if (!noerror) { count = 1; } + if (!retry) { count = 1; } if (align >= 0) { /* fill the rest of the ibuf with padding */ @@ -380,7 +382,7 @@ int main(int argc, char *argv[]) { t = io[1].bufuse; if (Io_write(&io[1])->bufuse == t - && !noerror + && !retry && io[1].error == 0) { (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)fprintio(stderr, fmt, io); - if(!noerror) { count = 1; } + if(!retry) { count = 1; } } } }