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41 lines
1.3 KiB
41 lines
1.3 KiB
8 years ago
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name: duk_opt_buffer
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proto: |
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void *duk_opt_buffer(duk_context *ctx, duk_idx_t idx, duk_size_t *out_size, void *def_ptr, duk_size_t def_len);
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stack: |
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[ ... val! ... ]
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summary: |
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<p>Get the data pointer for a (plain) buffer value at <code>idx</code> without
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modifying or coercing the value. Returns a non-<code>NULL</code> pointer if the value
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is a valid buffer with a non-zero size. For a zero-size buffer, may return a
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<code>NULL</code> or a non-<code>NULL</code> pointer. If <code>out_size</code> is
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non-<code>NULL</code>, the size of the buffer is written to <code>*out_size</code>.
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If the value is <code>undefined</code> or the index is invalid, <code>def_ptr</code>
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default value is returned and the <code>def_len</code> default length is written
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to <code>*out_size</code> (if <code>out_size</code> is non-<code>NULL</code>).
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In other cases (<code>null</code> and non-matching type) throws an error.</p>
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<div include="default-pointer-validity.html" />
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<div include="buffer-null-pointer-ambiguity.html" />
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example: |
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void *ptr;
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duk_size_t sz;
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char buf[256];
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/* Use a buffer given at index 2, or default to 'buf'. */
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ptr = duk_opt_buffer(ctx, 2, &sz, (void *) buf, sizeof(buf));
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printf("buf=%p, size=%lu\n", ptr, (unsigned long) sz);
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tags:
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- stack
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- buffer
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seealso:
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- duk_opt_buffer_data
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introduced: 2.1.0
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