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fix #3764

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This answer a static analysis tool,
which complains that a buffer allocation is not free() just before exit().

In general, this requirement is not necessary, because invoking exit() will make the OS reclaim all buffers from the terminated process.

I could articulate this new requirement in a "not too heavy" way with the use of a new macro, `CONTROL_EXIT()`.
But "not too heavy" is still a form of maintenance burden: whenever the code is modified, by adding, removing or changing some of these buffers, it requires some form of coordination with exit points, which is easy to let go wrong.
Besides, I wouldn't be surprised if there were some more complex scenarios left, typically across multiple levels of functions, where a call to `exit()` is made while some other buffers, inaccessible from the function, are still allocated. Tackling such issues would require a very different approach, typically forbidding the use of `exit()`, which was meant to simplify code maintenance by reducing the nb and complexity of error paths.
I question the need to make the code more complex to read and maintain, just to tackle a largely theoretical problem with no practical impact on target platforms.
This commit is contained in:
Yann Collet 2023-09-20 11:17:14 -07:00 committed by Yann Collet
parent c692b8d12d
commit bfeb456fcd
1 changed files with 12 additions and 7 deletions
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19
programs/util.c
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@ -53,12 +53,17 @@ extern "C" {
* It's designed for failures that may happen rarely,
* but we don't want to maintain a specific error code path for them,
* such as a malloc() returning NULL for example.
* Since it's always active, this macro can trigger side effects.
*/
#define CONTROL(c) { \
#define CONTROL(c) CONTROL_EXIT(c, {})
/* CONTROL_EXIT:
* Same as CONTROL, but can also run a last action before exit()
*/
#define CONTROL_EXIT(c, _action) { \
if (!(c)) { \
UTIL_DISPLAYLEVEL(1, "Error : %s, %i : %s", \
UTIL_DISPLAYLEVEL(1, "Error : %s, %i : %s not respected", \
__FILE__, __LINE__, #c); \
{ _action; } \
exit(1); \
} }
@ -685,7 +690,7 @@ UTIL_createFileNamesTable_fromFileName(const char* inputFileName)
}
{ const char** filenamesTable = (const char**) malloc(nbFiles * sizeof(*filenamesTable));
CONTROL(filenamesTable != NULL);
CONTROL_EXIT(filenamesTable != NULL, free(buf));
{ size_t fnb;
for (fnb = 0, pos = 0; fnb < nbFiles; fnb++) {
@ -774,12 +779,12 @@ UTIL_mergeFileNamesTable(FileNamesTable* table1, FileNamesTable* table2)
newTotalTableSize = getTotalTableSize(table1) + getTotalTableSize(table2);
buf = (char*) calloc(newTotalTableSize, sizeof(*buf));
CONTROL ( buf != NULL );
CONTROL_EXIT ( buf != NULL, UTIL_freeFileNamesTable(newTable) );
newTable->buf = buf;
newTable->tableSize = table1->tableSize + table2->tableSize;
newTable->fileNames = (const char **) calloc(newTable->tableSize, sizeof(*(newTable->fileNames)));
CONTROL ( newTable->fileNames != NULL );
CONTROL_EXIT ( newTable->fileNames != NULL, { free(buf); UTIL_freeFileNamesTable(newTable); } );
{ unsigned idx1;
for( idx1=0 ; (idx1 < table1->tableSize) && table1->fileNames[idx1] && (pos < newTotalTableSize); ++idx1, ++newTableIdx) {
@ -1266,7 +1271,7 @@ void UTIL_mirrorSourceFilesDirectories(const char** inFileNames, unsigned int nb
for (i = 0; i < nbFile; ++i) {
if (isFileNameValidForMirroredOutput(inFileNames[i])) {
char* fname = STRDUP(inFileNames[i]);
CONTROL(fname != NULL);
CONTROL_EXIT(fname != NULL, free(srcFileNames));
srcFileNames[validFilenamesNr++] = fname;
}
}