112 lines
2.2 KiB
C
112 lines
2.2 KiB
C
/* $Source$
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* $State$
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* $Revision$
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "libsys.h"
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struct for_main {
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int argc;
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char **argv;
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char **envp;
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};
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/*
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* Marshal the command line and environment variable data provided by
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* MS-DOS, into the standard format expected by a C main(...) routine. The
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* environment variable data has been copied to the near data segment.
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*
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* Return zero if everything went well, non-zero otherwise.
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*/
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int _sys_initmain(char *arg_data, size_t n_env_vars, char *env_data,
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unsigned msdos_ver_major, struct for_main *out)
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{
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char **argv, **envp;
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char c, *p, **pp;
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unsigned char n;
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/*
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* Allocate space for argv[] for the maximum possible number of
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* arguments. We can shrink this later.
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*/
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if ((argv = sbrk(65 * sizeof(char *))) == OUT_OF_MEMORY)
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return -1;
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out->argv = argv;
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/* Sanity-check the original command line. */
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p = arg_data;
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n = (unsigned char)*p;
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if (n > 0x7E || p[1 + n] != '\r')
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return -1;
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/* Initialize argv[0] to an empty string first. */
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*p = 0;
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argv[0] = p;
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/*
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* Split the command line string into separate arguments.
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* TODO: handle double-quoting, backslashes, etc.
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*/
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pp = argv + 1;
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do
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{
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do
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c = *++p;
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while (c == ' ' || c == '\t');
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if (c != '\r')
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{
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*pp++ = p;
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do
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c = *++p;
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while (c != ' ' && c != '\t' && c != '\r');
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*p = 0;
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}
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} while (c != '\r');
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/* Wrap up argv[]. Compute argc. Free up unneeded space. */
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out->argc = pp - argv;
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*pp++ = NULL;
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if (brk(pp) != 0)
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return -1;
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/* Allocate space for envp[]. */
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if ((envp = sbrk((n_env_vars + 1) * sizeof(char *))) == OUT_OF_MEMORY)
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return -1;
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out->envp = envp;
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/*
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* Populate envp[]. The environment data is simply a series of ASCIIZ
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* strings, one after another, terminated by an empty string.
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*/
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pp = envp;
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p = env_data;
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while (*p)
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{
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*pp++ = p;
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while (*++p);
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++p;
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}
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*pp = NULL;
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/*
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* If there is a program name (MS-DOS version is 3 or above), point
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* argv[0] to it.
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*
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* p points to the zero byte just before the count of strings (a
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* shortword) following the environment variables, so advance p by 3
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* bytes to get at the program name.
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*/
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if (msdos_ver_major >= 3)
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{
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p += 3;
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argv[0] = p;
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}
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/* We are done. */
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return 0;
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}
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