139 lines
5.4 KiB
C
139 lines
5.4 KiB
C
/* bt_dev.c — 蓝牙 A2DP 设备自识别（纯逻辑实现，见 bt_dev.h 契约）。
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*
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* 纯 libc（string / stdlib），无任何 meow_* 调用、无 popen、无文件 I/O —— meow_audiod 负责
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* 读取 /usr/data/alsa.conf、执行 `bluealsa-cli list-pcms` 及写回。宿主单测零链路重。
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*/
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#include "bt_dev.h"
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#include <string.h>
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#include <stdlib.h>
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#include <stdio.h>
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/* 解析 bluealsa-cli list-pcms 输出，取第一个 a2dpsrc/a2dp_source 端点的设备 MAC。
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* 端点形如 `a2dpsrc/AA:BB:CC:DD:EE:FF`（MAC 在端点 token 内最后一个 '/' 之后到空白前）。
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* 逐个**有界行**匹配（strstr 必须在行内，避免跨换行误把后一行当本行端点——如行 1
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* "profile/aptx" 与行 3 "a2dp_source/..." 的经典误判）。 */
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int bt_dev_detect_mac(const char *listpcms, char *mac, size_t macsz)
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{
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if (!listpcms || !mac || macsz < 2) return -1;
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mac[0] = 0;
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const char *ln = listpcms;
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while (ln && *ln) {
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const char *nl = strchr(ln, '\n');
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const char *le = nl ? nl : (ln + strlen(ln));
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size_t linelen = (size_t)(le - ln);
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char line[256];
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if (linelen >= sizeof line) linelen = sizeof line - 1;
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memcpy(line, ln, linelen); line[linelen] = 0;
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const char *p = line;
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while (*p == ' ' || *p == '\t') p++;
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const char *hit = strstr(p, "a2dpsrc");
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if (!hit) hit = strstr(p, "a2dp_source");
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if (hit) {
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const char *te = hit;
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while (*te && *te != ' ' && *te != '\t' && *te != '\n') te++;
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const char *slash = NULL;
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for (const char *q = hit; q < te; q++) if (*q == '/') slash = q;
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if (slash && (slash + 1) < te) {
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const char *start = slash + 1;
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size_t len = (size_t)(te - start);
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if (len > 0 && len < macsz) {
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memcpy(mac, start, len);
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mac[len] = 0;
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return 0;
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}
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}
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}
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if (!nl) break;
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ln = nl + 1;
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}
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return -1;
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}
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/* 在单行内把 anchor（"DEV=" / "device"）后的 MAC 值替换为 mac，保留引号风格。
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* 行未含 anchor → 返回 1（out=原样）；含 anchor → 写回新行并返回 0。 */
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static int line_replace_mac(char *out, size_t outsz, const char *line,
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const char *anchor, const char *mac)
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{
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const char *at = strstr(line, anchor);
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if (!at) { snprintf(out, outsz, "%s", line); return 1; }
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const char *vp = at + strlen(anchor);
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while (*vp == ' ' || *vp == '\t') vp++;
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if (*vp == '"') vp++; /* 引号风格：值可带双引号 */
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const char *ve = vp;
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while (*ve && *ve != ' ' && *ve != '\t' && *ve != '\n' &&
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*ve != '"' && *ve != '{' && *ve != '}') ve++;
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size_t prefix = (size_t)(vp - line); /* 前段（含开引号，若带） */
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size_t tail = (size_t)(ve - line); /* 值终点（不含闭引号，若带） */
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/* 前段 + mac + 尾段（尾段保留闭引号与其后内容） */
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snprintf(out, outsz, "%.*s%s%s", (int)prefix, line, mac, line + tail);
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return 0;
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}
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/* 幂等改写 alsa.conf：只把 `pcm.bluealsa` 块内 `DEV=` 与 `device` 后的 MAC 换成 mac。
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* 逐行处理；无 pcm.bluealsa / 无 DEV= / device token → -1；两端已一致 → 1；改了 → 0。 */
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int bt_dev_rewrite(const char *in, size_t in_len, const char *mac,
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char **out, size_t *out_len)
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{
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if (!in || !mac || !mac[0] || !out || !out_len || in_len == 0) return -1;
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if (!strstr(in, "pcm.bluealsa") ||
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(!strstr(in, "DEV=") && !strstr(in, "device"))) return -1;
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size_t cap = in_len + 128;
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char *res = malloc(cap ? cap : 1);
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if (!res) return -1;
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size_t o = 0, changed = 0;
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const char *p = in, *end = in + in_len;
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while (p < end) {
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const char *nl = memchr(p, '\n', (size_t)(end - p));
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const char *le = nl ? nl : end;
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size_t linelen = (size_t)(le - p);
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char line[512], newline[512];
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if (linelen >= sizeof line) linelen = sizeof line - 1;
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memcpy(line, p, linelen); line[linelen] = 0;
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const char *k = line;
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while (*k == ' ' || *k == '\t') k++;
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int anchored = 0;
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if (strstr(k, "DEV=")) {
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line_replace_mac(newline, sizeof newline, line, "DEV=", mac);
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anchored = 1;
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} else if (strncmp(k, "device", 6) == 0 &&
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(k[6] == ' ' || k[6] == '\t' || k[6] == 0)) {
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line_replace_mac(newline, sizeof newline, line, "device", mac);
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anchored = 1;
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}
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if (anchored) {
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if (strcmp(line, newline) != 0) changed = 1;
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size_t n = strlen(newline);
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if (o + n + 2 > cap) {
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cap = o + n + 256;
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char *t = realloc(res, cap);
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if (!t) { free(res); return -1; }
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res = t;
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}
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memcpy(res + o, newline, n); o += n;
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if (nl) res[o++] = '\n';
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} else {
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size_t n = linelen;
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if (o + n + 2 > cap) {
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cap = o + n + 256;
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char *t = realloc(res, cap);
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if (!t) { free(res); return -1; }
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res = t;
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}
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memcpy(res + o, p, n); o += n;
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if (nl) res[o++] = '\n';
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}
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if (!nl) break;
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p = nl + 1;
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}
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if (!changed) { free(res); return 1; }
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res[o] = 0;
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*out = res;
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*out_len = o;
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return 0;
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}
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