From 9c1e0d785d76ff092f21e2643eb1fda60e553fcc Mon Sep 17 00:00:00 2001 From: DTB Date: Mon, 22 Apr 2024 07:52:41 -0600 Subject: [PATCH] pg(1): add -p option --- docs/pg.1 | 13 +++++++ src/pg.c | 109 +++++++++++++++++++++++++++++++++++------------------- 2 files changed, 84 insertions(+), 38 deletions(-) diff --git a/docs/pg.1 b/docs/pg.1 index 1a68e1c..72f09c1 100644 --- a/docs/pg.1 +++ b/docs/pg.1 @@ -9,10 +9,23 @@ pg \(en paginate +.SH SYNOPSIS + +pg +.RB ( -p +.RB [ prompt ]) + .SH DESCRIPTION Pg prints standard input to standard output, accepting commands between pages. +.SH OPTIONS + +.B -p +.RS +Replaces the default prompt (": ") with the next argument. +.RE + .SH DIAGNOSTICS Pg returns an unsuccessful exit code if the tty couldn't be opened or if pg was diff --git a/src/pg.c b/src/pg.c index 79aff64..4bcf0a0 100644 --- a/src/pg.c +++ b/src/pg.c @@ -22,11 +22,14 @@ * NULL */ #include /* size_t */ #include /* strchr(3), strcmp(3), strerror(3), strtok(3) */ +#include /* getopt(3) */ #if !defined EX_OK || !defined EX_SOFTWARE || !defined EX_USAGE # include #endif +#define CMDLINE_MAX 99+1 /* Maximum length of command line. */ + /* Done while looking at plan9ports' src/cmd/p.c. * Taken from plan9 are the interface (minus p(1)'s shell escaping and the * ability to page multiple files) and the practice of reading /dev/tty to get @@ -46,48 +49,64 @@ static char *program_name = "pg"; /* Commands start with cmd_. They take an argc and NULL-terminated argv, like * main, and return one of the following RET_ enums as a status. */ -enum{ RET_ARGSERROR, RET_OK, RET_NOCMD, RET_REQSHUTDOWN, RET_SOFTWARE }; +enum{ RET_OK, RET_REQSHUTDOWN, RET_USAGE, RET_NOCMD, RET_SOFTWARE }; -static int page_bytes(FILE *f, size_t l){ +/* Page at most l bytes from f without consideration of a buffer (print them to + * stdout). */ +static int pg_b_u(FILE *f, size_t l){ int c; while((c = fgetc(f)) != EOF) if((c = fputc(c, stdout)) == EOF || --l == 0) break; - return c == EOF - ? RET_REQSHUTDOWN - : RET_OK; + return c; } -static int page_lines(FILE *f, size_t l){ +/* Page at most l lines, which are lengths of characters terminated by nl, from + * f without consideration of a buffer (print them to stdout). */ +static int pg_l_u(FILE *f, size_t l, char nl){ int c; while((c = fgetc(f)) != EOF) - if((c = fputc(c, stdout)) == EOF || (l -= (c == '\n')) == 0) + if((c = fputc(c, stdout)) == EOF || (l -= (c == nl)) == 0) break; - return c == EOF - ? RET_REQSHUTDOWN - : RET_OK; + return c; } static int cmd_quit(int argc, char **argv){ return RET_REQSHUTDOWN; } static int cmd_default_page(int argc, char **argv){ - if(strtok(NULL, whitespace) != NULL) - return RET_ARGSERROR; /* This shouldn't be possible. */ + if(argc > 1) /* This shouldn't be possible. */ + return RET_USAGE; if(default_page_unit.type == BYTES) - return page_bytes(input, default_page_unit.quantity); + return pg_b_u(input, default_page_unit.quantity) == EOF + ? RET_REQSHUTDOWN + : RET_OK; else if(default_page_unit.type == LINES) - return page_lines(input, default_page_unit.quantity); + return pg_l_u(input, default_page_unit.quantity, '\n') == EOF + ? RET_REQSHUTDOWN + : RET_OK; else return RET_SOFTWARE; } +static int cmd_page_down_lines(int argc, char **argv){ + + switch(argc){ + case 1: + return cmd_default_page(argc, argv); + case 2: /* not implemented */ + default: + fprintf(stderr, "Usage: %s" /*" (lines)"*/ "\n", argv[0]); + return RET_USAGE; + } +} /* A CmdMap must be NULL-terminated. */ static struct CmdMap{ char *name; int (*fn)(int, char **); } cmd_map[] = { { "", cmd_default_page }, + { "+", cmd_page_down_lines }, /* don't make the user feel trapped */ { "exit", cmd_quit }, { "q", cmd_quit }, { ":q", cmd_quit }, @@ -100,6 +119,9 @@ static struct CmdMap{ char *name; int (*fn)(int, char **); } cmd_map[] = { /* Find and execute the command in the command map, given a corresponding * command line. */ static int cmdline_exec(struct CmdMap *map, char *cmdline){ + /* Command line word splitting is naive and based on whitespace ONLY; no + * fancy quoting or escaping here. Adding that would (ideally) entail + * replacing strtok(3) with something specific to this task. */ static int argc; static char *argv[ARGV_MAX]; @@ -109,7 +131,7 @@ static int cmdline_exec(struct CmdMap *map, char *cmdline){ argv[argc] = cmdline; argv[++argc] = NULL; }else{ - while((argv[++argc] = strtok(NULL , whitespace)) != NULL + while((argv[++argc] = strtok(NULL, whitespace)) != NULL && argc < ARGV_MAX); } @@ -121,49 +143,60 @@ static int cmdline_exec(struct CmdMap *map, char *cmdline){ return RET_NOCMD; } +int usage(char *s){ + fprintf(stderr, "Usage: %s (-p [prompt])\n", s); + return EX_USAGE; +} + int main(int argc, char *argv[]){ - unsigned char cmd[99+1]; - int r; + unsigned char cmd[CMDLINE_MAX]; FILE *t; input = stdin; - if(argc > 0) + if(argc < 1) program_name = argv[0]; + else{ + int c; - if(argc > 1){ - fprintf(stderr, "Usage: %s\n", program_name); - return EX_USAGE; + while((c = getopt(argc, argv, "p:")) != -1) + switch(c){ + case 'p': prompt = optarg; break; + default: + return usage(program_name); + } } + if(argc > optind) + return usage(program_name); + + if((t = fopen("/dev/tty", "rb")) == NULL){ fprintf(stderr, "%s: /dev/tty: %s\n", program_name, strerror(errno)); return EX_SOFTWARE; } - r = 0; for(;;){ - if(r != RET_REQSHUTDOWN){ - fputs(prompt, stderr); - fgets((char *)cmd, (sizeof cmd) / (sizeof *cmd), t); - if(strchr((char *)cmd, '\n') == NULL){ /* fast-forward stream */ - int c; + fputs(prompt, stderr); + fgets((char *)cmd, (sizeof cmd) / (sizeof *cmd), t); + if(strchr((char *)cmd, '\n') == NULL){ /* fast-forward stream */ + int c; - while((c = fgetc(t)) != '\n') - if(c == EOF) - break; - } + while((c = fgetc(t)) != '\n') + if(c == EOF) + break; } - if(r == RET_REQSHUTDOWN || feof(t)){ - fclose(t); + + if(feof(t)) return EX_OK; - } - switch((r = cmdline_exec(cmd_map, (char *)cmd))){ - case RET_ARGSERROR: case RET_NOCMD: case RET_OK: + switch(cmdline_exec(cmd_map, (char *)cmd)){ + case RET_USAGE: case RET_NOCMD: case RET_OK: break; - case RET_REQSHUTDOWN: case RET_SOFTWARE: default: - r = RET_REQSHUTDOWN; + case RET_SOFTWARE: + return EX_SOFTWARE; + case RET_REQSHUTDOWN: default: + return EX_OK; } }