WebSVN – SvarDOS – Diff – /svarcom/trunk/command.c



#define CMDLINE_MAXLEN 255
 
 
/* sets guard values at a few places in memory for later detection of
 * overflows via memguard_check() */
static void memguard_set(char *cmdlinebuf) {
  BUFFER[sizeof(BUFFER) - 1] = 0xC7;
  cmdlinebuf[CMDLINE_MAXLEN] = 0xC7;
}
 
 
/* checks for valguards at specific memory locations, returns 0 on success */
static int memguard_check(unsigned short rmodseg, char *cmdlinebuf) {
  /* check RMOD signature (would be overwritten in case of stack overflow */
  static char msg[] = "!! MEMORY CORRUPTION ## DETECTED !!";
  unsigned short far *rmodsig = MK_FP(rmodseg, 0x100 + 6);
  if (*rmodsig != 0x2019) {
    msg[22] = '1';
    outputnl(msg);
    printf("rmodseg = %04X ; *rmodsig = %04X\r\n", rmodseg, *rmodsig);
    return(1);
  }
  /* check last BUFFER byte */
  if (BUFFER[sizeof(BUFFER) - 1] != 0xC7) {
    msg[22] = '2';
    outputnl(msg);
    return(2);
  }
  /* check last cmdlinebuf byte */
  if (cmdlinebuf[CMDLINE_MAXLEN] != 0xC7) {
    msg[22] = '3';
    outputnl(msg);
    return(3);
  }
  /* all good */

int main(void) {
  static struct config cfg;
  static unsigned short far *rmod_envseg;
  static unsigned short far *lastexitcode;
  static struct rmod_props far *rmod;
  static char cmdlinebuf[CMDLINE_MAXLEN + 2]; /* 1 extra byte for 0-terminator and another for memguard */
  static char *cmdline;
 
  rmod = rmod_find(BUFFER_len);
  if (rmod == NULL) {
    /* look at command line parameters (in case env size if set there) */

     * have a purpose in life */
    if (rmod->flags & FLAG_EXEC_AND_QUIT) sayonara(rmod);
  }
 
  /* install a few guardvals in memory to detect some cases of overflows */
  memguard_set(cmdlinebuf);
 
  rmod_envseg = MK_FP(rmod->rmodseg, RMOD_OFFSET_ENVSEG);
  lastexitcode = MK_FP(rmod->rmodseg, RMOD_OFFSET_LEXITCODE);
 
  /* make COMPSEC point to myself */

 
    /* cancel any redirections that may have been set up before */
    redir_revert();
 
    /* memory check */
    memguard_check(rmod->rmodseg, cmdlinebuf);
 
    /* preset cmdline to point at the dedicated buffer */
 
    cmdline = cmdlinebuf;
 
    /* (re)load translation strings if needed */
    nls_langreload(BUFFER, *rmod_envseg);
 
    /* skip user input if I have a command to exec (/C or /K) */

      outputnl("");
      continue;
    }
 
    /* try matching (and executing) an internal command */
    if (cmd_process(rmod, *rmod_envseg, cmdline, BUFFER, sizeof(BUFFER)) >= -1) {
      /* internal command executed */
      redir_revert(); /* revert stdout (in case it was redirected) */
      continue;
    }
 

Rev 494	Rev 500
Line 50...	Line 50...
50	`#define CMDLINE_MAXLEN 255`	50	`#define CMDLINE_MAXLEN 255`
51		51
52		52
53	`/* sets guard values at a few places in memory for later detection of`	53	`/* sets guard values at a few places in memory for later detection of`
54	`* overflows via memguard_check() */`	54	`* overflows via memguard_check() */`
55	`static void memguard_set(void) {`	55	`static void memguard_set(char *cmdlinebuf) {`
56	`BUFFER[sizeof(BUFFER) - 1] = 0xC7;`	56	`BUFFER[sizeof(BUFFER) - 1] = 0xC7;`
57	`BUFFER[sizeof(BUFFER) - (CMDLINE_MAXLEN + 3)] = 0xC7;`	57	`cmdlinebuf[CMDLINE_MAXLEN] = 0xC7;`
58	`}`	58	`}`
59		59
60		60
61	`/* checks for valguards at specific memory locations, returns 0 on success */`	61	`/* checks for valguards at specific memory locations, returns 0 on success */`
62	`static int memguard_check(unsigned short rmodseg) {`	62	`static int memguard_check(unsigned short rmodseg, char *cmdlinebuf) {`
63	`/* check RMOD signature (would be overwritten in case of stack overflow */`	63	`/* check RMOD signature (would be overwritten in case of stack overflow */`
64	`static char msg[] = "!! MEMORY CORRUPTION ## DETECTED !!";`	64	`static char msg[] = "!! MEMORY CORRUPTION ## DETECTED !!";`
65	`unsigned short far *rmodsig = MK_FP(rmodseg, 0x100 + 6);`	65	`unsigned short far *rmodsig = MK_FP(rmodseg, 0x100 + 6);`
66	`if (*rmodsig != 0x2019) {`	66	`if (*rmodsig != 0x2019) {`
67	`msg[22] = '1';`	67	`msg[22] = '1';`
68	`outputnl(msg);`	68	`outputnl(msg);`
69	`printf("rmodseg = %04X ; rmodsig = %04X\r\n", rmodseg, rmodsig);`	69	`printf("rmodseg = %04X ; rmodsig = %04X\r\n", rmodseg, rmodsig);`
70	`return(1);`	70	`return(1);`
71	`}`	71	`}`
72	`/* check last BUFFER byte (could be overwritten by cmdline) */`	72	`/* check last BUFFER byte */`
73	`if (BUFFER[sizeof(BUFFER) - 1] != 0xC7) {`	73	`if (BUFFER[sizeof(BUFFER) - 1] != 0xC7) {`
74	`msg[22] = '2';`	74	`msg[22] = '2';`
75	`outputnl(msg);`	75	`outputnl(msg);`
76	`return(2);`	76	`return(2);`
77	`}`	77	`}`
78	`/* check that cmdline BUFFER's end hasn't been touched by something else */`	78	`/* check last cmdlinebuf byte */`
79	`if (BUFFER[sizeof(BUFFER) - (CMDLINE_MAXLEN + 3)] != 0xC7) {`	79	`if (cmdlinebuf[CMDLINE_MAXLEN] != 0xC7) {`
80	`msg[22] = '3';`	80	`msg[22] = '3';`
81	`outputnl(msg);`	81	`outputnl(msg);`
82	`return(3);`	82	`return(3);`
83	`}`	83	`}`
84	`/* all good */`	84	`/* all good */`
Line 612...	Line 612...
612	`int main(void) {`	612	`int main(void) {`
613	`static struct config cfg;`	613	`static struct config cfg;`
614	`static unsigned short far *rmod_envseg;`	614	`static unsigned short far *rmod_envseg;`
615	`static unsigned short far *lastexitcode;`	615	`static unsigned short far *lastexitcode;`
616	`static struct rmod_props far *rmod;`	616	`static struct rmod_props far *rmod;`
-		617	`static char cmdlinebuf[CMDLINE_MAXLEN + 2]; /* 1 extra byte for 0-terminator and another for memguard */`
617	`static char *cmdline;`	618	`static char *cmdline;`
618		619
619	`rmod = rmod_find(BUFFER_len);`	620	`rmod = rmod_find(BUFFER_len);`
620	`if (rmod == NULL) {`	621	`if (rmod == NULL) {`
621	`/* look at command line parameters (in case env size if set there) */`	622	`/* look at command line parameters (in case env size if set there) */`
Line 635...	Line 636...
635	`* have a purpose in life */`	636	`* have a purpose in life */`
636	`if (rmod->flags & FLAG_EXEC_AND_QUIT) sayonara(rmod);`	637	`if (rmod->flags & FLAG_EXEC_AND_QUIT) sayonara(rmod);`
637	`}`	638	`}`
638		639
639	`/* install a few guardvals in memory to detect some cases of overflows */`	640	`/* install a few guardvals in memory to detect some cases of overflows */`
640	`memguard_set();`	641	`memguard_set(cmdlinebuf);`
641		642
642	`rmod_envseg = MK_FP(rmod->rmodseg, RMOD_OFFSET_ENVSEG);`	643	`rmod_envseg = MK_FP(rmod->rmodseg, RMOD_OFFSET_ENVSEG);`
643	`lastexitcode = MK_FP(rmod->rmodseg, RMOD_OFFSET_LEXITCODE);`	644	`lastexitcode = MK_FP(rmod->rmodseg, RMOD_OFFSET_LEXITCODE);`
644		645
645	`/* make COMPSEC point to myself */`	646	`/* make COMPSEC point to myself */`
Line 667...	Line 668...
667		668
668	`/* cancel any redirections that may have been set up before */`	669	`/* cancel any redirections that may have been set up before */`
669	`redir_revert();`	670	`redir_revert();`
670		671
671	`/* memory check */`	672	`/* memory check */`
672	`memguard_check(rmod->rmodseg);`	673	`memguard_check(rmod->rmodseg, cmdlinebuf);`
673		674
674	`/* preset cmdline to point at the end of my general-purpose buffer (with`	675	`/* preset cmdline to point at the dedicated buffer */`
675	`* one extra byte for the NULL terminator and another for memguard val) */`	-
676	`cmdline = BUFFER + sizeof(BUFFER) - (CMDLINE_MAXLEN + 2);`	676	`cmdline = cmdlinebuf;`
677		677
678	`/* (re)load translation strings if needed */`	678	`/* (re)load translation strings if needed */`
679	`nls_langreload(BUFFER, *rmod_envseg);`	679	`nls_langreload(BUFFER, *rmod_envseg);`
680		680
681	`/* skip user input if I have a command to exec (/C or /K) */`	681	`/* skip user input if I have a command to exec (/C or /K) */`
Line 731...	Line 731...
731	`outputnl("");`	731	`outputnl("");`
732	`continue;`	732	`continue;`
733	`}`	733	`}`
734		734
735	`/* try matching (and executing) an internal command */`	735	`/* try matching (and executing) an internal command */`
736	`if (cmd_process(rmod, *rmod_envseg, cmdline, BUFFER) >= -1) {`	736	`if (cmd_process(rmod, *rmod_envseg, cmdline, BUFFER, sizeof(BUFFER)) >= -1) {`
737	`/* internal command executed */`	737	`/* internal command executed */`
738	`redir_revert(); /* revert stdout (in case it was redirected) */`	738	`redir_revert(); /* revert stdout (in case it was redirected) */`
739	`continue;`	739	`continue;`
740	`}`	740	`}`
741		741

Subversion Repositories SvarDOS

(root)/svarcom/trunk/command.c @ 1202 – Rev 494 → 500