写一个C语言的7z解压缩接口

以下是一个基本的 C 语言 7z 解压缩接口的示例代码，它使用了 7-Zip C SDK 提供的 API：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <7z.h>
#include <7zCrc.h>
#include <7zFile.h>

#define kInputBufSize ((size_t)1 << 18)

int extract7zFile(const char *inFilePath, const char *outDirPath) {
    int res = 0;
    HANDLE hFile = NULL;
    int open_res = 0;
    CSzArEx db;
    ISzAlloc allocImp;
    ISzAlloc allocTempImp;
    size_t len;
    CrcGenerateTable();
    allocImp.Alloc = SzAlloc;
    allocImp.Free = SzFree;
    allocTempImp.Alloc = SzAllocTemp;
    allocTempImp.Free = SzFreeTemp;
    if (InFile_Open(&hFile, inFilePath) != 0) {
        return -1;
    }
    SzArEx_Init(&db);
    open_res = SzArEx_Open(&db, hFile, &allocImp, &allocTempImp);
    if (open_res == SZ_OK) {
        UInt32 i;
        size_t blockIndex = 0xFFFFFFFF; /* it can have any value before first call (if outBuffer = 0) */
        Byte *outBuffer = 0; /* it must be 0 before first call for each new archive. */
        size_t outBufferSize = 0;  /* it can have any value before first call (if outBuffer = 0) */
        UInt32 numErrors = 0;
        for (i = 0; i < db.NumFiles; i++) {
            size_t offset = 0;
            size_t outSizeProcessed = 0;
            size_t outSize = 0;
            CSzFile outFile;
            size_t len;
            int isDir = SzArEx_IsDir(&db, i);
            len = SzArEx_GetFileNameUtf16(&db, i, NULL);
            if (len > 0) {
                int *temp = (int *)malloc(len);
                SzArEx_GetFileNameUtf16(&db, i, temp);
                // convert filename from utf-16 to utf-8
                char *fileName = (char *)malloc(len * 2 + 1);
                wcstombs(fileName, (wchar_t *)temp, len * 2 + 1);
                if (isDir) {
                    char outPath[MAX_PATH];
                    sprintf(outPath, "%s/%s", outDirPath, fileName);
                    mkdir(outPath, 0777);
                } else {
                    res = SzArEx_Extract(&db, hFile, i,
                        &blockIndex, &outBuffer, &outBufferSize,
                        &offset, &outSizeProcessed, &outSize,
                        &allocImp, &allocTempImp);
                    if (res == SZ_OK) {
                        char outPath[MAX_PATH];
                        sprintf(outPath, "%s/%s", outDirPath, fileName);
                        File_Construct(&outFile);
                        File_Open(&outFile, outPath, FILE_CREATE | FILE_WRITE);
                        File_Write(&outFile, outBuffer + offset, outSize);
                        File_Close(&outFile);
                    } else {
                        numErrors++;
                    }
                }
                free(fileName);
                free(temp);
            }
            SzFree(NULL, outBuffer);
            outBuffer = 0;
            outBufferSize = 0;
        }
        if (numErrors == 0) {
            res = 0;
        } else {
            res = -1;
        }
    } else {
        res = -1;
    }
    SzArEx_Free(&db, &allocImp);
    InFile_Close(hFile);
    return res;
}

上述代码中，extract7zFile() 函数接受两个参数：输入文件路径和输出目录路径。该函数首先打开输入文件，并使用 7-Zip C SDK 提供的 SzArEx_Open() 函数打开 7z 文件，并读取文件列表。

然后，对于每个文件，它检查它是否是一个目录，如果是，就在输出目录中创建一个相应的子目录。如果不是目录，就使用 SzArEx_Extract() 函数从 7z 文件中提取文件，并将其写入到输出目录中。在写入文件之前，还需要将文件名从 UTF-16 编码转换为 UTF-8 编码。

最后，该函数关闭输入文件，释放 7-Zip C SDK 分配的内存，并返回一个整数值，表示提取操作的结果。