timoreo/quirc
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Align image memory on page

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This commit is contained in:
graindcafe 2021-12-25 12:49:57 +01:00
parent 516d91a94d
commit e35fa50e48
1 changed files with 15 additions and 11 deletions
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26
lib/quirc.c
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@ -17,6 +17,7 @@
#include <stdlib.h> #include <stdlib.h>
#include <string.h> #include <string.h>
#include "quirc_internal.h" #include "quirc_internal.h"
#include <sys/mman.h>
const char *quirc_version(void) const char *quirc_version(void)
{ {
@ -36,7 +37,7 @@ struct quirc *quirc_new(void)
void quirc_destroy(struct quirc *q) void quirc_destroy(struct quirc *q)
{ {
free(q->image); munmap(q->image, q->w * q->h);
/* q->pixels may alias q->image when their type representation is of the /* q->pixels may alias q->image when their type representation is of the
same size, so we need to be careful here to avoid a double free */ same size, so we need to be careful here to avoid a double free */
if (!QUIRC_PIXEL_ALIAS_IMAGE) if (!QUIRC_PIXEL_ALIAS_IMAGE)
@ -62,20 +63,22 @@ int quirc_resize(struct quirc *q, int w, int h)
if (w < 0 || h < 0) if (w < 0 || h < 0)
goto fail; goto fail;
/*
* alloc a new buffer for q->image. We avoid realloc(3) because we want
* on failure to be leave `q` in a consistant, unmodified state.
*/
image = calloc(w, h);
if (!image)
goto fail;
/* compute the "old" (i.e. currently allocated) and the "new" /* compute the "old" (i.e. currently allocated) and the "new"
(i.e. requested) image dimensions */ (i.e. requested) image dimensions */
size_t olddim = q->w * q->h; size_t olddim = q->w * q->h;
size_t newdim = w * h; size_t newdim = w * h;
size_t min = (olddim < newdim ? olddim : newdim); size_t min = (olddim < newdim ? olddim : newdim);
/*
* alloc a new buffer for q->image. We avoid realloc(3) because we want
* on failure to be leave `q` in a consistant, unmodified state.
* mmap will ensure memory page alignment
*/
image = mmap(NULL, newdim, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (!image)
goto fail;
memset(image, 0, newdim);
/* /*
* copy the data into the new buffer, avoiding (a) to read beyond the * copy the data into the new buffer, avoiding (a) to read beyond the
* old buffer when the new size is greater and (b) to write beyond the * old buffer when the new size is greater and (b) to write beyond the
@ -120,7 +123,7 @@ int quirc_resize(struct quirc *q, int w, int h)
/* alloc succeeded, update `q` with the new size and buffers */ /* alloc succeeded, update `q` with the new size and buffers */
q->w = w; q->w = w;
q->h = h; q->h = h;
free(q->image); munmap(q->image, olddim);
q->image = image; q->image = image;
if (!QUIRC_PIXEL_ALIAS_IMAGE) { if (!QUIRC_PIXEL_ALIAS_IMAGE) {
free(q->pixels); free(q->pixels);
@ -133,7 +136,8 @@ int quirc_resize(struct quirc *q, int w, int h)
return 0; return 0;
/* NOTREACHED */ /* NOTREACHED */
fail: fail:
free(image); if (image != NULL)
munmap(image, newdim);
free(pixels); free(pixels);
free(vars); free(vars);