sdk: 图片层追加预算解码入口,JPEG 解码期缩解(峰值 43.7→14.0 MiB)

M6 finding(vuln/high):meow_img_load_file 必先整幅 RGBA 解码,1600×2400 漫画页
瞬时峰值 20.2 MiB(15.4 MiB 输出 + 5.5 MiB YCbCr 平面),超设备 ~14MB 口径,
App 侧无法规避。

调研(vendored stb v2.30):无解码期缩放能力——JPEG 走固定 hs/vs 重采样到全尺寸,
PNG 一次性 inflate 整幅 raw_image,公共 API 只有 load/load_16/loadf/info。
完整缩小 IDCT 需改编 1/2、1/4、1/8 IDCT + 进升级系数存储 + MCU 尺寸,改动面大且
易出静默像素错误,故不重写解码器。

改为受控的最小追加(sdk/stb_image.h):
- 新增 stbi_load_scaled / stbi_load_scaled_from_memory:JPEG 输出级按步长 s 抽取
  行/列(resample 状态机逐行推进,仅采样行做颜色转换),整幅原尺寸输出缓冲从不
  物化;scale<=1 与旧 API 逐字节等价,非 JPEG 忽略。
- 进升级 JPEG:各分量系数 IDCT 进像素平面后立即释放(原来拖到输出分配之后)。
- 旧公共 API 行为不变。

SDK 追加式入口(旧 API 一字未改):
- meow_img_load_file_dim / meow_img_load_mem_dim(path/buf, maxdim):stbi_info 头探测
  选 1/2、1/4、1/8 整数档(取「长边/s ≥ maxdim」最大档,不欠采样),再交既有
  meow_img_downscale 精修;小图/maxdim<=0 走旧路径。
- meow_img_probe_file:只读头取尺寸,供 App 在 OOM 前提示。

实测(宿主 test_meow_img_budget,--wrap malloc 打点,全部 PASS):
  8.32MP JPEG   43.70 → 13.96 MiB(新/旧 0.32)
  1600×2400 页  20.16 →  9.18 MiB
  progressive   43.70 → 35.83 MiB(系数阵列扫描期驻留,残余上限)
  PNG 2400×1600 25.65 → 25.65 MiB(stb 无 PNG 缩解,如实记录)
  BMP 2400×1600 14.65 → 15.23 MiB(同上,多一次降采样小缓冲)
缩解结果与「整幅解码+downscale」网格平均差 6.28;对 PIL 逐像素比对与全幅解码
同误差量级(mean ≤0.02, max ≤3)。

验证:build_sdk.sh 重编 meow_ui.a 0 warning;examples/hello 重链 0 warning;
tuku 用 MEOW_SDK_DIR 指向本分支 sdk 重链 0 warning;既有 test_meow_img_color 仍全 PASS。
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/* test_meow_img_budget.c — M12 预算解码(meow_img_load_file_dim / _mem_dim)宿主验证。
*
* 覆盖矩阵(对齐 M12 任务 3/4):
* B1 探针:meow_img_probe_file 只读头取原始尺寸(8.32MP 图),坏图/不存在返回 0
* B2 小图不动:64x64 走旧路径,与 meow_img_load_file 逐字节相同;maxdim<=0 等价旧入口
* B3 长边约束:8.32MP baseline JPEG 在 maxdim=480/300/128/64 下结果两维都 ≤ maxdim,长宽比保持
* B4 峰值对比:同一 8.32MP JPEG「旧入口 vs 新入口」瞬时分配峰值(--wrap malloc 打点),
* 断言新入口峰值 < 旧入口 1/2;B4b 极端 maxdim=100;B4c finding 原始场景 1600x2400 页
* B5 内容正确:新入口结果与「旧入口整幅解码 + meow_img_downscale」网格采样比对(平均差阈值)
* B6 进升级:progressive JPEG 走同一缩解路径(峰值记录 + 长边约束)
* B7 内存入口:meow_img_load_mem_dim 与文件入口等价(峰值 < 旧内存入口 1/2)
* B8 坏图:坏 JPEG(魔数+垃圾)/ 空内存 / 不存在路径 → NULL(不崩)
* B9 PNG/BMP:尺寸约束成立,峰值如实记录(stb 无解码期缩放 → 与旧入口同级)
*
* 夹具(生成一次):
* python3 test_meow_img_budget_gen.py "$PREFIX/tmp/meow_img_budget"
* 编译(本 sdk 目录下;--wrap 用于给 malloc/free 家族打点):
* gcc -Wall -Wextra -I. -Iinclude -DMEOW_UI_HOST_TEST -o test_meow_img_budget \
* test_meow_img_budget.c meow_ui_img.c stb_image.c -lm \
* -Wl,--wrap=malloc -Wl,--wrap=calloc -Wl,--wrap=realloc -Wl,--wrap=free
* 运行:./test_meow_img_budget "$PREFIX/tmp/meow_img_budget" (exit 0=PASS / 1=FAIL)
* 夹具目录可省略:默认 $PREFIX/tmp/meow_img_budget;缺失时自动调 gen 脚本生成。
*/
#define _GNU_SOURCE
#include "meow_ui.h"
#include "meow_ui_internal.h" /* meow_gfx_blit_rgba 原型(本测试只给桩) */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <sys/stat.h>
/* ------------------------------------------------------------------ */
/* 分配打点:--wrap malloc/free 家族,记录「存活字节」与峰值 */
/* ------------------------------------------------------------------ */
#define AHDR 32 /* 头部长度:保留原始大小,保证 16 字节对齐 */
static size_t g_live = 0;
static size_t g_peak = 0;
extern void *__real_malloc(size_t);
extern void *__real_calloc(size_t, size_t);
extern void *__real_realloc(void *, size_t);
extern void __real_free(void *);
static void acc_alloc(size_t n)
{
g_live += n;
if (g_live > g_peak) g_peak = g_live;
}
void *__wrap_malloc(size_t n)
{
size_t *h = (size_t *)__real_malloc(n + AHDR);
if (!h) return NULL;
h[0] = n;
acc_alloc(n);
return (char *)h + AHDR;
}
void *__wrap_calloc(size_t a, size_t b)
{
size_t n = a * b;
void *p = __wrap_malloc(n);
if (p) memset(p, 0, n);
return p;
}
void __wrap_free(void *p)
{
size_t *h;
if (!p) return;
h = (size_t *)((char *)p - AHDR);
g_live -= h[0];
__real_free(h);
}
void *__wrap_realloc(void *p, size_t n)
{
size_t old = p ? ((size_t *)((char *)p - AHDR))[0] : 0;
void *q = __wrap_malloc(n);
if (!q) return NULL;
if (p) {
memcpy(q, p, old < n ? old : n);
__wrap_free(p);
}
return q;
}
static size_t peak_reset(void) { g_peak = g_live; return g_live; }
static size_t peak_since(size_t base) { return g_peak - base; }
/* meow_ui_img.c 的绘制函数需要的 gfx 符号:本测试只测解码/内存,桩即可。 */
void meow_gfx_blit_rgba(int x, int y, int w, int h, const uint8_t *rgba, int alpha)
{
(void)x; (void)y; (void)w; (void)h; (void)rgba; (void)alpha;
}
/* ------------------------------------------------------------------ */
/* 断言与打印 */
/* ------------------------------------------------------------------ */
static int g_fail = 0;
#define CHECK(cond, name) do { \
if (cond) printf(" PASS %s\n", name); \
else { printf(" FAIL %s (%s:%d)\n", name, __FILE__, __LINE__); g_fail++; } } while (0)
static void peak_report(const char *tag, size_t bytes)
{
printf(" peak %-28s %8.2f MiB (%zu B)\n", tag, (double)bytes / (1024.0 * 1024.0), bytes);
}
/* ------------------------------------------------------------------ */
/* 路径与夹具 */
/* ------------------------------------------------------------------ */
static const char *g_dir = NULL;
static char *path_join(const char *name)
{
size_t n = strlen(g_dir) + strlen(name) + 2;
char *p = (char *)malloc(n);
if (!p) { printf("OOM\n"); exit(1); }
snprintf(p, n, "%s/%s", g_dir, name);
return p;
}
static int file_exists(const char *p)
{
struct stat st;
return stat(p, &st) == 0 && st.st_size > 0;
}
static void ensure_fixtures(void)
{
char *big = path_join("big.jpg");
if (file_exists(big)) { free(big); return; }
free(big);
printf("夹具缺失,尝试 python3 test_meow_img_budget_gen.py %s\n", g_dir);
{
char cmd[1024];
snprintf(cmd, sizeof cmd, "python3 test_meow_img_budget_gen.py '%s'", g_dir);
if (system(cmd) != 0)
printf(" 生成失败(缺 Pillow?)——请按头注释手动生成\n");
}
}
static uint8_t *read_whole(const char *p, size_t *len)
{
FILE *f = fopen(p, "rb");
uint8_t *buf;
long n;
if (!f) return NULL;
fseek(f, 0, SEEK_END);
n = ftell(f);
fseek(f, 0, SEEK_SET);
if (n <= 0) { fclose(f); return NULL; }
buf = (uint8_t *)malloc((size_t)n);
if (!buf) { fclose(f); return NULL; }
if (fread(buf, 1, (size_t)n, f) != (size_t)n) { free(buf); fclose(f); return NULL; }
fclose(f);
*len = (size_t)n;
return buf;
}
/* ------------------------------------------------------------------ */
/* 图像辅助 */
/* ------------------------------------------------------------------ */
static int nonblank(const meow_img *im)
{
int w = meow_img_w(im), h = meow_img_h(im);
const unsigned char *p = meow_img_pixels(im);
long sum = 0;
if (!p || w <= 0 || h <= 0) return 0;
for (long i = 0; i < (long)w * h; i += 97)
sum += p[i * 4] + p[i * 4 + 1] + p[i * 4 + 2];
return sum > 0;
}
/* 按比例网格采样比对两图(尺寸可不同):返回各通道平均绝对差。 */
static double mean_abs_diff(const meow_img *a, const meow_img *b, int grid)
{
int wa = meow_img_w(a), ha = meow_img_h(a);
int wb = meow_img_w(b), hb = meow_img_h(b);
const unsigned char *pa = meow_img_pixels(a), *pb = meow_img_pixels(b);
long acc = 0, cnt = 0;
if (!pa || !pb || wa <= 0 || hb <= 0) return 1e9;
for (int gy = 0; gy < grid; gy++) {
int ya = (int)((long)gy * ha / grid);
int yb = (int)((long)gy * hb / grid);
for (int gx = 0; gx < grid; gx++) {
int xa = (int)((long)gx * wa / grid);
int xb = (int)((long)gx * wb / grid);
const unsigned char *qa = pa + ((size_t)ya * wa + xa) * 4;
const unsigned char *qb = pb + ((size_t)yb * wb + xb) * 4;
for (int k = 0; k < 3; k++) {
int d = (int)qa[k] - (int)qb[k];
acc += d < 0 ? -d : d;
cnt++;
}
}
}
return cnt ? (double)acc / (double)cnt : 1e9;
}
/* ================================================================== */
int main(int argc, char **argv)
{
char *p_big, *p_prog, *p_small, *p_png, *p_bmp, *p_broken, *p_missing;
size_t peak_old, peak_new;
if (argc > 1) {
g_dir = argv[1];
} else {
/* Termux 的 /tmp 不可写:优先 $TMPDIR,其次 $PREFIX/tmp。 */
static char dflt[600];
const char *tmp = getenv("TMPDIR");
const char *pre = getenv("PREFIX");
if (tmp && *tmp) snprintf(dflt, sizeof dflt, "%s/meow_img_budget", tmp);
else if (pre && *pre) snprintf(dflt, sizeof dflt, "%s/tmp/meow_img_budget", pre);
else snprintf(dflt, sizeof dflt, "/tmp/meow_img_budget");
g_dir = dflt;
}
ensure_fixtures();
p_big = path_join("big.jpg");
p_prog = path_join("bigprog.jpg");
p_small = path_join("small.jpg");
p_png = path_join("big.png");
p_bmp = path_join("big.bmp");
p_broken = path_join("broken.jpg");
p_missing = path_join("no_such_file.jpg");
if (!file_exists(p_big)) {
printf("FATAL 夹具 %s 不存在(先跑 test_meow_img_budget_gen.py)\n", p_big);
return 1;
}
/* ---- B1 探针 ---- */
printf("[B1] 头探测(零像素内存)\n");
{
int w = 0, h = 0, c = 0;
CHECK(meow_img_probe_file(p_big, &w, &h, &c) == 1, "probe 成功");
CHECK(w == 3200 && h == 2600, "probe 原始尺寸 3200x2600");
CHECK(c == 3, "probe 通道数 3");
printf(" probe → %dx%d ch=%d\n", w, h, c);
CHECK(meow_img_probe_file(p_broken, NULL, NULL, NULL) == 0, "probe 截断图 → 0");
CHECK(meow_img_probe_file(p_missing, NULL, NULL, NULL) == 0, "probe 不存在 → 0");
CHECK(meow_img_probe_file(NULL, NULL, NULL, NULL) == 0, "probe NULL → 0");
}
/* ---- B2 小图不动 ---- */
printf("[B2] 小图不动 / maxdim<=0 等价旧入口\n");
{
meow_img *a = meow_img_load_file(p_small);
meow_img *b = meow_img_load_file_dim(p_small, 64);
meow_img *z = meow_img_load_file_dim(p_small, 0);
CHECK(a && b && z, "小图三条路径都成功");
CHECK(meow_img_w(b) == meow_img_w(a) && meow_img_h(b) == meow_img_h(a),
"maxdim=64 → 尺寸不变");
CHECK(b && a && meow_img_w(a) * meow_img_h(a) > 0 &&
memcmp(meow_img_pixels(a), meow_img_pixels(b),
(size_t)meow_img_w(a) * meow_img_h(a) * 4) == 0,
"小图逐字节与旧入口一致");
CHECK(z && a && memcmp(meow_img_pixels(a), meow_img_pixels(z),
(size_t)meow_img_w(a) * meow_img_h(a) * 4) == 0,
"maxdim=0 等价旧入口(逐字节)");
meow_img_free(a); meow_img_free(b); meow_img_free(z);
}
/* ---- B3 长边约束 ---- */
printf("[B3] 8.32MP baseline JPEG 长边约束\n");
{
static const int dims[] = { 480, 300, 128, 64 };
int wi = 0, hi = 0;
meow_img *full = meow_img_load_file(p_big);
CHECK(full != NULL, "旧入口解码成功");
if (full) { wi = meow_img_w(full); hi = meow_img_h(full); }
printf(" 原图 %dx%d (%.2f MP)\n", wi, hi, (double)wi * hi / 1e6);
for (size_t i = 0; i < sizeof dims / sizeof dims[0]; i++) {
meow_img *s = meow_img_load_file_dim(p_big, dims[i]);
char name[96];
snprintf(name, sizeof name, "maxdim=%d → 两维 ≤ maxdim 且非空", dims[i]);
CHECK(s && meow_img_w(s) <= dims[i] && meow_img_h(s) <= dims[i] && nonblank(s), name);
if (s) {
double ar0 = (double)wi / hi, ar1 = (double)meow_img_w(s) / meow_img_h(s);
CHECK(ar1 > ar0 * 0.98 && ar1 < ar0 * 1.02, "长宽比保持(±2%)");
printf(" maxdim=%-4d → %dx%d\n", dims[i], meow_img_w(s), meow_img_h(s));
}
meow_img_free(s);
}
meow_img_free(full);
}
/* ---- B4 峰值对比(JPEG) ---- */
printf("[B4] 瞬时分配峰值:旧入口 vs 新入口(同一 8.32MP JPEG)\n");
{
size_t base = peak_reset();
meow_img *old = meow_img_load_file(p_big);
peak_old = peak_since(base);
base = peak_reset();
meow_img *nw = meow_img_load_file_dim(p_big, 480);
peak_new = peak_since(base);
CHECK(old && nw, "两条路径都成功");
peak_report("旧入口 meow_img_load_file", peak_old);
peak_report("新入口 _dim(480)", peak_new);
printf(" 整幅 RGBA 理论值 = %.2f MiB;新/旧 = %.2f\n",
(double)meow_img_w(old) * meow_img_h(old) * 4 / (1024.0 * 1024.0),
(double)peak_new / (double)peak_old);
CHECK(peak_new * 2 < peak_old, "新入口峰值 < 旧入口 1/2(不物化整幅 RGBA)");
CHECK(peak_new < (size_t)20 * 1024 * 1024, "新入口峰值 < 20 MiB(8.32MP 页可加载)");
/* B5 内容正确性:新 vs 旧整幅 + downscale 精修 */
if (old && nw) {
meow_img *ref = meow_img_downscale(old, 480);
double d = mean_abs_diff(nw, ref ? ref : old, 64);
printf(" 与「旧入口+downscale」网格平均差 = %.2f\n", d);
CHECK(d < 20.0, "缩解内容结构一致(平均差 < 20)");
meow_img_free(ref);
}
meow_img_free(old);
meow_img_free(nw);
}
/* ---- B4b 极端 maxdim ---- */
printf("[B4b] maxdim=100(8 倍缩解档位 + 精修)\n");
{
size_t base = peak_reset();
meow_img *s = meow_img_load_file_dim(p_big, 100);
size_t peak = peak_since(base);
CHECK(s && meow_img_w(s) <= 100 && meow_img_h(s) <= 100 && nonblank(s), "结果 ≤100 且非空");
peak_report("_dim(100)", peak);
CHECK(peak * 2 < peak_old, "峰值仍 < 旧入口 1/2");
meow_img_free(s);
}
/* ---- B4c finding 原始场景 ---- */
printf("[B4c] finding 原始场景:1600x2400 漫画页\n");
{
char *p_page = path_join("page.jpg");
if (file_exists(p_page)) {
size_t base = peak_reset();
meow_img *old = meow_img_load_file(p_page);
size_t p_old = peak_since(base);
base = peak_reset();
meow_img *nw = meow_img_load_file_dim(p_page, 720);
size_t p_new = peak_since(base);
CHECK(old && nw, "1600x2400 两条路径都成功");
if (nw)
CHECK(meow_img_w(nw) <= 720 && meow_img_h(nw) <= 720 && nonblank(nw),
"结果 ≤720 且非空");
if (old)
printf(" 整幅 RGBA 理论值 = %.2f MiB\n",
(double)meow_img_w(old) * meow_img_h(old) * 4 / (1024.0 * 1024.0));
peak_report("旧入口 page.jpg", p_old);
peak_report("新入口 _dim(720)", p_new);
CHECK(p_new < (size_t)10 * 1024 * 1024, "新入口峰值 < 10 MiB(设备 ~14MB 口径内)");
meow_img_free(old);
meow_img_free(nw);
} else {
printf(" SKIP page.jpg(夹具缺失)\n");
}
free(p_page);
}
/* ---- B6 进升级 JPEG ---- */
printf("[B6] progressive JPEG(同一缩解路径)\n");
{
size_t base = peak_reset();
meow_img *old = meow_img_load_file(p_prog);
size_t p_old = peak_since(base);
base = peak_reset();
meow_img *nw = meow_img_load_file_dim(p_prog, 480);
size_t p_new = peak_since(base);
CHECK(old && nw, "进升级两条路径都成功");
CHECK(nw && meow_img_w(nw) <= 480 && meow_img_h(nw) <= 480 && nonblank(nw),
"进升级结果 ≤480 且非空");
peak_report("旧入口 progressive", p_old);
peak_report("新入口 _dim(480) progressive", p_new);
CHECK(p_new < p_old, "进升级峰值下降(系数阵列仍在扫描期驻留,见报告)");
meow_img_free(old);
meow_img_free(nw);
}
/* ---- B7 内存入口 ---- */
printf("[B7] 内存入口 meow_img_load_mem_dim(CBZ/档案页场景)\n");
{
size_t len = 0;
uint8_t *buf = read_whole(p_big, &len);
CHECK(buf != NULL, "读入 8.32MP JPEG 到内存");
if (buf) {
size_t base = peak_reset();
meow_img *old = meow_img_load_mem(buf, (int)len);
size_t p_old = peak_since(base);
base = peak_reset();
meow_img *nw = meow_img_load_mem_dim(buf, (int)len, 480);
size_t p_new = peak_since(base);
CHECK(old && nw, "内存入口两条路径都成功");
CHECK(nw && meow_img_w(nw) <= 480 && nonblank(nw), "内存入口结果 ≤480 且非空");
peak_report("旧 meow_img_load_mem", p_old);
peak_report("新 meow_img_load_mem_dim", p_new);
CHECK(p_new * 2 < p_old, "内存入口峰值 < 旧入口 1/2");
meow_img_free(old);
meow_img_free(nw);
free(buf);
}
}
/* ---- B8 坏图 ---- */
printf("[B8] 坏图容错\n");
{
size_t len = 0;
uint8_t *buf;
CHECK(meow_img_load_file_dim(p_broken, 480) == NULL, "截断 JPEG → NULL");
CHECK(meow_img_load_file_dim(p_missing, 480) == NULL, "不存在路径 → NULL");
CHECK(meow_img_load_file_dim(NULL, 480) == NULL, "NULL 路径 → NULL");
buf = read_whole(p_broken, &len);
CHECK(buf && meow_img_load_mem_dim(buf, (int)len, 480) == NULL, "截断 JPEG 内存入口 → NULL");
free(buf);
CHECK(meow_img_load_mem_dim("x", 3, 480) == NULL, "垃圾内存 → NULL");
}
/* ---- B9 PNG / BMP(stb 无解码期缩放,如实记录峰值) ---- */
printf("[B9] PNG / BMP:尺寸约束成立,峰值如实记录(stb 无解码期缩放)\n");
{
struct { const char *tag; const char *path; } fx[] = {
{ "PNG", p_png }, { "BMP", p_bmp },
};
for (size_t i = 0; i < sizeof fx / sizeof fx[0]; i++) {
if (!file_exists(fx[i].path)) {
printf(" SKIP %s(夹具缺失)\n", fx[i].tag);
continue;
}
{
size_t base = peak_reset();
meow_img *old = meow_img_load_file(fx[i].path);
size_t p_old = peak_since(base);
meow_img *nw;
char name[96];
base = peak_reset();
nw = meow_img_load_file_dim(fx[i].path, 480);
{
size_t p_new = peak_since(base);
snprintf(name, sizeof name, "%s _dim(480) 两维 ≤480 且非空", fx[i].tag);
CHECK(nw && meow_img_w(nw) <= 480 && meow_img_h(nw) <= 480 && nonblank(nw), name);
peak_report(fx[i].tag, p_old);
peak_report(" ↑ 新入口", p_new);
snprintf(name, sizeof name, "%s 峰值与旧入口同级(stb 无解码期缩放)", fx[i].tag);
CHECK(p_new <= p_old + p_old / 8, name);
if (old) printf(" %s 原图 %dx%d\n", fx[i].tag, meow_img_w(old), meow_img_h(old));
meow_img_free(nw);
}
meow_img_free(old);
}
}
}
if (g_fail) printf("\nRESULT: FAIL (%d)\n", g_fail);
else printf("\nRESULT: ALL PASS\n");
free(p_big); free(p_prog); free(p_small); free(p_png);
free(p_bmp); free(p_broken); free(p_missing);
return g_fail ? 1 : 0;
}