interp_parse.c revision 38789
138716Smsmith/* 238716Smsmith * Redistribution and use in source and binary forms, with or without 338716Smsmith * modification, are permitted provided that the following conditions 438716Smsmith * are met: 538716Smsmith * 1. Redistributions of source code must retain the above copyright 638716Smsmith * notice, this list of conditions and the following disclaimer. 738716Smsmith * 2. Redistributions in binary form must reproduce the above copyright 838716Smsmith * notice, this list of conditions and the following disclaimer in the 938716Smsmith * documentation and/or other materials provided with the distribution. 1038716Smsmith * 1138716Smsmith * Jordan K. Hubbard 1238716Smsmith * 29 August 1998 1338716Smsmith * 1438789Smsmith * $Id: interp_parse.c,v 1.2 1998/09/03 06:14:41 jkh Exp $ 1538716Smsmith * 1638716Smsmith * The meat of the simple parser. 1738716Smsmith */ 1838716Smsmith 1938716Smsmith#include <stand.h> 2038716Smsmith#include <string.h> 2138716Smsmith 2238716Smsmith/* Forward decls */ 2338716Smsmithextern char *backslash(char *str); 2438716Smsmith 2538716Smsmithstatic void init(int *argcp, char ***argvp); 2638716Smsmithstatic void clean(void); 2738716Smsmithstatic int insert(int *argcp, char *buf); 2838716Smsmithstatic char *variable_lookup(char *name); 2938716Smsmith 3038716Smsmith#define PARSE_BUFSIZE 1024 /* maximum size of one element */ 3138716Smsmith#define MAXARGS 20 /* maximum number of elements */ 3238716Smsmithstatic char *args[MAXARGS]; 3338716Smsmith 3438716Smsmith/* 3538716Smsmith * parse: accept a string of input and "parse" it for backslash 3638716Smsmith * substitutions and environment variable expansions (${var}), 3738716Smsmith * returning an argc/argv style vector of whitespace separated 3838716Smsmith * arguments. Returns 0 on success, 1 on failure (ok, ok, so I 3938716Smsmith * wimped-out on the error codes! :). 4038716Smsmith * 4138716Smsmith * Note that the argv array returned must be freed by the caller, but 4238716Smsmith * we own the space allocated for arguments and will free that on next 4338716Smsmith * invocation. This allows argv consumers to modify the array if 4438716Smsmith * required. 4538716Smsmith * 4638716Smsmith * NB: environment variables that expand to more than one whitespace 4738716Smsmith * separated token will be returned as a single argv[] element, not 4838716Smsmith * split in turn. Expanded text is also immune to further backslash 4938716Smsmith * elimination or expansion since this is a one-pass, non-recursive 5038716Smsmith * parser. You didn't specify more than this so if you want more, ask 5138716Smsmith * me. - jkh 5238716Smsmith */ 5338716Smsmith 5438716Smsmith#define PARSE_FAIL(expr) \ 5538716Smsmithif (expr) { \ 5638716Smsmith printf("fail at line %d\n", __LINE__); \ 5738716Smsmith clean(); \ 5838716Smsmith free(copy); \ 5938716Smsmith free(buf); \ 6038716Smsmith return 1; \ 6138716Smsmith} 6238716Smsmith 6338716Smsmith/* Accept the usual delimiters for a variable, returning counterpart */ 6438716Smsmithstatic char 6538716Smsmithisdelim(char ch) 6638716Smsmith{ 6738716Smsmith if (ch == '{') 6838716Smsmith return '}'; 6938716Smsmith else if (ch == '(') 7038716Smsmith return ')'; 7138716Smsmith return '\0'; 7238716Smsmith} 7338716Smsmith 7438765Sjkhstatic int 7538765Sjkhisquote(char ch) 7638765Sjkh{ 7738765Sjkh return (ch == '\'' || ch == '"'); 7838765Sjkh} 7938765Sjkh 8038716Smsmithint 8138716Smsmithparse(int *argc, char ***argv, char *str) 8238716Smsmith{ 8338716Smsmith int ac; 8438716Smsmith char *val, *p, *q, *copy = NULL; 8538716Smsmith int i = 0; 8638765Sjkh char token, tmp, quote, *buf; 8738716Smsmith enum { STR, VAR, WHITE } state; 8838716Smsmith 8938716Smsmith ac = *argc = 0; 9038765Sjkh quote = 0; 9138716Smsmith if (!str || (p = copy = backslash(str)) == NULL) 9238716Smsmith return 1; 9338716Smsmith 9438716Smsmith /* Initialize vector and state */ 9538716Smsmith clean(); 9638716Smsmith state = STR; 9738765Sjkh buf = (char *)malloc(PARSE_BUFSIZE); 9838716Smsmith token = 0; 9938716Smsmith 10038716Smsmith /* And awaaaaaaaaay we go! */ 10138716Smsmith while (*p) { 10238716Smsmith switch (state) { 10338716Smsmith case STR: 10438765Sjkh if (isquote(*p)) { 10538765Sjkh quote = quote ? 0 : *p; 10638765Sjkh ++p; 10738765Sjkh } 10838765Sjkh else if (isspace(*p) && !quote) { 10938716Smsmith state = WHITE; 11038716Smsmith if (i) { 11138716Smsmith buf[i] = '\0'; 11238716Smsmith PARSE_FAIL(insert(&ac, buf)); 11338716Smsmith i = 0; 11438716Smsmith } 11538716Smsmith ++p; 11638716Smsmith } else if (*p == '$') { 11738716Smsmith token = isdelim(*(p + 1)); 11838716Smsmith if (token) 11938716Smsmith p += 2; 12038716Smsmith else 12138716Smsmith ++p; 12238716Smsmith state = VAR; 12338716Smsmith } else { 12438716Smsmith PARSE_FAIL(i == (PARSE_BUFSIZE - 1)); 12538716Smsmith buf[i++] = *p++; 12638716Smsmith } 12738716Smsmith break; 12838716Smsmith 12938716Smsmith case WHITE: 13038716Smsmith if (isspace(*p)) 13138716Smsmith ++p; 13238716Smsmith else 13338716Smsmith state = STR; 13438716Smsmith break; 13538716Smsmith 13638716Smsmith case VAR: 13738716Smsmith if (token) { 13838716Smsmith PARSE_FAIL((q = index(p, token)) == NULL); 13938716Smsmith } else { 14038716Smsmith q = p; 14138716Smsmith while (*q && !isspace(*q)) 14238716Smsmith ++q; 14338716Smsmith } 14438716Smsmith tmp = *q; 14538716Smsmith *q = '\0'; 14638716Smsmith if ((val = variable_lookup(p)) != NULL) { 14738716Smsmith int len = strlen(val); 14838716Smsmith 14938716Smsmith strncpy(buf + i, val, PARSE_BUFSIZE - (i + 1)); 15038789Smsmith i += min(len, PARSE_BUFSIZE - 1); 15138716Smsmith } 15238716Smsmith *q = tmp; /* restore value */ 15338716Smsmith p = q + (token ? 1 : 0); 15438716Smsmith state = STR; 15538716Smsmith break; 15638716Smsmith } 15738716Smsmith } 15838716Smsmith /* If at end of token, add it */ 15938716Smsmith if (i && state == STR) { 16038716Smsmith buf[i] = '\0'; 16138716Smsmith PARSE_FAIL(insert(&ac, buf)); 16238716Smsmith } 16338716Smsmith args[ac] = NULL; 16438716Smsmith *argc = ac; 16538765Sjkh *argv = (char **)malloc((sizeof(char *) * ac + 1)); 16638716Smsmith bcopy(args, *argv, sizeof(char *) * ac + 1); 16738716Smsmith free(copy); 16838716Smsmith return 0; 16938716Smsmith} 17038716Smsmith 17138716Smsmith#define MAXARGS 20 17238716Smsmith 17338716Smsmith/* Clean vector space */ 17438716Smsmithstatic void 17538716Smsmithclean(void) 17638716Smsmith{ 17738716Smsmith int i; 17838716Smsmith 17938716Smsmith for (i = 0; i < MAXARGS; i++) { 18038716Smsmith if (args[i] != NULL) { 18138716Smsmith free(args[i]); 18238716Smsmith args[i] = NULL; 18338716Smsmith } 18438716Smsmith } 18538716Smsmith} 18638716Smsmith 18738716Smsmithstatic int 18838716Smsmithinsert(int *argcp, char *buf) 18938716Smsmith{ 19038716Smsmith if (*argcp >= MAXARGS) 19138716Smsmith return 1; 19238716Smsmith args[(*argcp)++] = strdup(buf); 19338716Smsmith return 0; 19438716Smsmith} 19538716Smsmith 19638716Smsmithstatic char * 19738716Smsmithvariable_lookup(char *name) 19838716Smsmith{ 19938716Smsmith /* XXX search "special variable" space first? */ 20038716Smsmith return (char *)getenv(name); 20138716Smsmith} 202