Revision 6e9ea0c0 block-vpc.c
| b/block-vpc.c | ||
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* |
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* Note that the geometry doesn't always exactly match total_sectors but |
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* may round it down. |
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* |
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* Returns 0 on success, -EFBIG if the size is larger than 127 GB |
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*/ |
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static void calculate_geometry(int64_t total_sectors, uint16_t* cyls,
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static int calculate_geometry(int64_t total_sectors, uint16_t* cyls,
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uint8_t* heads, uint8_t* secs_per_cyl) |
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{
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uint32_t cyls_times_heads; |
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if (total_sectors > 65535 * 16 * 255) |
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total_sectors = 65535 * 16 * 255;
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return -EFBIG;
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if (total_sectors > 65535 * 16 * 63) {
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*secs_per_cyl = 255; |
| ... | ... | |
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// Note: Rounding up deviates from the Virtual PC behaviour |
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// However, we need this to avoid truncating images in qemu-img convert |
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*cyls = (cyls_times_heads + *heads - 1) / *heads; |
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return 0; |
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} |
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static int vpc_create(const char *filename, int64_t total_sectors, |
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return -EIO; |
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// Calculate matching total_size and geometry |
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calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl); |
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if (calculate_geometry(total_sectors, &cyls, &heads, &secs_per_cyl)) |
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return -EFBIG; |
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total_sectors = (int64_t) cyls * heads * secs_per_cyl; |
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// Prepare the Hard Disk Footer |
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