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config: delete variable only if it makes enough space to write new

This commit is contained in:
C. Masloch 2023-08-30 11:30:16 +02:00 committed by Kenneth J Davis
parent 6101fb2aed
commit 95694f7e34
1 changed files with 10 additions and 4 deletions
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14
kernel/config.c
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@ -2768,22 +2768,28 @@ STATIC VOID CmdSet(BYTE *pLine)
pLine = skipwh(pLine); /* scan() stops at the equal sign or space */ pLine = skipwh(pLine); /* scan() stops at the equal sign or space */
if (*pLine == '=') /* equal sign is required */ if (*pLine == '=') /* equal sign is required */
{ {
int size, namesize; int size, oldsize, namesize;
BYTE far * pp; BYTE far * pp;
strupr(szBuf); /* all environment variables must be uppercase */ strupr(szBuf); /* all environment variables must be uppercase */
namesize = strlen(szBuf); namesize = strlen(szBuf);
strcat(szBuf, "="); strcat(szBuf, "=");
pp = searchvar(szBuf, namesize); pp = searchvar(szBuf, namesize);
deletevar(pp);
pLine = skipwh(++pLine); pLine = skipwh(++pLine);
strcat(szBuf, pLine); /* append the variable value (may include spaces) */ strcat(szBuf, pLine); /* append the variable value (may include spaces) */
size = strlen(szBuf); size = strlen(szBuf);
if (size == namesize + 1) { if (size == namesize + 1) {
/* empty variable ? then just delete. */ /* empty variable ? then just delete. (cannot fail) */
deletevar(pp);
return; return;
} }
if (size < master_env + sizeof(master_env) - envp - 1 - 2) if (pp) {
oldsize = fstrlen(pp) + 1;
} else {
oldsize = 0;
}
if (size < master_env + sizeof(master_env) - (envp - oldsize) - 1 - 2)
{ /* must end with two consequtive zeros */ { /* must end with two consequtive zeros */
deletevar(pp); /* now that there's enough space, actually delete */
fstrcpy(envp, szBuf); fstrcpy(envp, szBuf);
envp += size + 1; /* add next variables starting at the second zero */ envp += size + 1; /* add next variables starting at the second zero */
*envp = 0; *envp = 0;